feat(examples): EngineShowcase flagship + persistent rasterizer (Phase B+C)

[DemchaAV]

Summary

Phases B + C of the pre-v1.6.6 presentation polish plan. Phase A (the broken docs/index.html asset paths) merged earlier as #101.

Before the Maven Central debut an external visual-presentation audit flagged two things on the README hero asset (assets/readme/repository_showcase_render.png):

• The render felt dated — single-page, sparse, didn't show what v1.6.x can do.
• The hero was not generated from anything in the repo — a stale binary committed once, no story behind it.

This PR fixes both with one flagship example + a tiny persistent helper.

Phase B — RepositoryHeroShowcase flagship

examples/src/main/java/com/demcha/examples/flagships/RepositoryHeroShowcase.java (~200 LOC) renders a two-page editorial CV via the MintEditorial v2 preset, driven by a meta-narrative dataset:

Mariia Demchyshyn — Senior Software Engineer · Document Engine Author

The engine renders its own author's CV. The data is substantive — no Lorem ipsum, no template-fill repeats — so a reader who lands on the README hero sees what the engine actually produces, not what a preset's placeholder looks like.

What the hero shows in one glance:

Feature	Where it appears
Themed masthead band (pageBackgrounds + theme tokens)	Top of page 1 — centred spaced-caps name + mint accent rule
Two-column page geometry (v2 layered slots)	Sidebar (Contact / Interests / Skills / Education) vs. body (Profile / Experience)
Mixed section kinds	Paragraph, Entries, Skills (with proficiency bars), Rows
Cross-page deterministic pagination	Experience continues onto page 2 with sidebar refresh
Icon-augmented contact list	Phone, email, location, web, GitHub, LinkedIn, Twitter

Listed in the examples gallery README under the 🚀 Start here tier.

Phase C — PdfPageRasterizer helper + hero swap

examples/src/main/java/com/demcha/examples/support/PdfPageRasterizer.java (~60 LOC) is a tiny PDFBox-based CLI that rasterises one page of a PDF into a PNG at a chosen DPI. Lets the repo regenerate any hero / social-card image without depending on Ghostscript, ImageMagick, or pdftoppm — none of which are reliably available on a stock Windows Git Bash. Reused for any future README image regeneration.

./mvnw -B -ntp -f examples/pom.xml -DskipTests exec:java \
    -Dexec.mainClass=com.demcha.examples.support.PdfPageRasterizer \
    -Dexec.args="<inputPdf> <outputPng> [pageIndex0=0] [dpi=200]"

assets/readme/repository_showcase_render.png regenerated from page 1 of the new flagship (1818 × 2572 px at 220 DPI; 358 KB — down from 478 KB).

Visual verification cycle

Rendered the PDF, rasterised page 1 to PNG, opened the PNG directly through Claude:

Iteration	Issue	Fix
v1 (Rose Harris MintEditorial)	Page 1 already polished but content was Lorem ipsum + three identical "DEGREE/BACHELOR" rows — read like a template preview, not a real artefact	Author new flagship with bespoke realistic data
v2 (Mariia Demchyshyn first pass)	Sidebar labels wrapping mid-letter: DETERMINISTIC RENDERIN/G, OPEN-SOURCE STEWARDSH/IP, M.SC. COMPUTER SCIENC/E, B.SC. SOFTWARE ENGINE/ERING	Shortened labels: DETERMINISM, OSS STEWARDSHIP, MSC COMPUTER SCIENCE, BSC SOFTWARE ENG.
v3 (current)	All labels fit cleanly; no mid-word breaks; substantive content; sidebar geometry stable	Shipped

What this doesn't do

• Does not restructure the README itself — the auditor's P0.2 (wide hero banner) / P0.3 (reorder Install above comparison) / P1 (collage of 3 best screenshots) / P2 (visual-language unification) are a separate workstream. They are not v1.6.6 blockers.
• Does not regenerate every Pages site asset — that was Phase A (docs/index.html path repair, #101).

Verification

$ ./mvnw -B -ntp test -pl . \
    -Dtest='CanonicalSurfaceGuardTest,DocumentationCoverageTest,DocumentationExamplesTest,VersionConsistencyGuardTest'
Tests run: 13, Failures: 0, Errors: 0, Skipped: 0

Doc guards green. CHANGELOG entry added to v1.6.6 — Planned ### Documentation.

Test plan

• New flagship compiles and renders
• Page 1 rasterises cleanly (PdfPageRasterizer)
• Visual inspection iterated 3 times; no mid-word wraps, no Lorem ipsum
• Hero PNG replaced in assets/readme/
• Gallery entry added to examples/README.md
• Doc guards green locally
• CI green on PR (Guards / JDK 17/21/25 / Examples Smoke / no-poi / japicmp / binary-compat)
• Reviewer skim — visual diff on the PNG, flagship code shape, rasterizer placement
• (Out of scope) follow-up: README structural rewrite (auditor's P0.2 / P0.3 / P1) — separate v1.6.7 polish workstream

[DemchaAV]

Pivot: replaced the meta-narrative CV flagship with EngineShowcase — a cinematic single-page brand promo that exercises rounded clip-frames, classpath-loaded hero imagery, softPanel + accent-rule cards, and mixed serif/sans typography. The CV register was the wrong one for the README hero asset — it competed with the actual CV gallery rather than complementing it. The new hero reads as the engine's brand register.

Render: examples/target/generated-pdfs/flagships/engine-showcase.pdf -> page 1 rasterised to assets/readme/repository_showcase_render.png (1653x2338 px, 200 DPI, 2.1 MB).

Doc + version guards: CanonicalSurfaceGuardTest + DocumentationExamplesTest + DocumentationCoverageTest + VersionConsistencyGuardTest = 30/0/0 green locally.

Branch force-pushed: 8e1b8409..dee0bf77.

[DemchaAV]

Content tightened per directive: all about engine capabilities + performance + the logo.

Headline lockup — One engine. / Every PDF you ship. — frames the engine as the proposition, not the format.

KPI cards now report engine scale (all verifiable counts, no manufactured latency):

• 31 V2 PRESETS — layered preset architecture (16 CV + 15 cover letter)
• 1,033 TESTS · 0 FAILURES — snapshot baselines, japicmp gate, JMH suite
• 17 SEMANTIC PRIMITIVES — every node themable + snapshot-tested

Capability columns:

• DECLARATIVE BY DESIGN — zero PDFBox imports in app code
• DETERMINISTIC RENDER — identical input → identical PDF, byte-comparable
• CINEMATIC THEMING — BusinessTheme · CvTheme palettes + v2 layered presets

The brand artwork is the hero asset — semantic-graph → polished-PDFs visual metaphor in the 516×280 rounded clip-frame. GRAPHCOMPOSE wordmark in the marquee, v1.6 · MAVEN CENTRAL aligned right.

Re-rasterised assets/readme/repository_showcase_render.png (1653×2338 px). Branch dee0bf77..808a5fce.

[DemchaAV]

Visual polish round:

1. Hero frame stroke 0.8pt -> 2.5pt — the brand artwork now reads with a confident orange rule around it, framed like a magazine cover rather than a hairline edge.
2. Capability columns get a tinted backing panel — PANEL_TINT (lavender rgb 232/234/246) with a slightly darker ring (rgb 208/214/234). Cool counterpoint to the warm cream paper, ties back to the navy brand, and makes the orange accent rule pop.
3. Text shifted right of the accent rule — capability section left padding 0 -> 16pt, accent rule 2.5pt -> 3.0pt. Text now sits with breathing room instead of crowding the rule.

Re-rasterised assets/readme/repository_showcase_render.png. Branch 808a5fce..1c0f33a4.

[DemchaAV]

Уголки фикс. Артефакт был от взаимодействия thick stroke на rounded path с clipPolicy(CLIP_PATH) — на углах виден square notch вместо чистого скругления.

Решение: убрал stroke полностью, заменил на два вложенных rounded-rect'а:

• Внешний: 519x287 r=16 fillColor(ACCENT) — служит рамкой
• Внутренний: 513x281 r=13 fillColor(NAVY_DARK) clipPolicy(CLIP_PATH) — держит картинку

Видимый 3pt оранжевый бордюр по периметру — равномерный, углы идеально круглые, никаких stroke-vs-clip конфликтов.

Это и есть canonical-pattern для thick borders на rounded shapes в GraphCompose: nested fills вместо thick stroke. Branch 1c0f33a4..be076b88.

[DemchaAV]

Tab-on-left callout фикс: левые углы капабилити-панелей теперь square (где сидит оранжевая полоска), правые остаются rounded.

Замена: softPanel(PANEL_TINT, 6, 0) -> softPanel(PANEL_TINT, DocumentCornerRadius.right(6), 0). Параллельно убрал тонкий ring (PANEL_RING stroke 0.5) — на нем тот же thick-stroke-on-rounded-path риск, и панель и без него читается чисто на тёплом кремовом фоне.

Этот pattern — tab-on-left callouts — каноничный для случая когда есть accent rule + rounded panel: левая сторона square (rule сидит flush на ровной грани), правая rounded. Никаких пересечений straight line с curve.

Branch be076b88..776847d2.