[codex] Update v3.4 website, samples, daemon hosting, and forms runtime

[MaxAkbar]

Summary

This PR broadens the v3.4.0 website/docs cleanup into a fuller sample and
runtime-hosting pass.

On the website side, the repo now preserves the source-heavy markdown guides
under companion source-reference HTML pages and removes only the duplicated
markdown files that were verified as safe to delete. The site work also adds a
new blog post covering the C# launcher pattern for CSharpDB.Admin.

On the sample side, this PR adds samples/fulfillment-hub, a runnable
operations showcase that seeds relational schema, views, triggers, procedures,
saved queries, Admin forms, Admin reports, stored pipelines, typed collections,
and a full-text index into one sample database. The sample README is now a
guided story walkthrough so users can learn the platform by running through a
day in warehouse operations instead of reading a flat checklist.

This PR also adds src/CSharpDB.Admin.Forms.Web, a forms-only web host that
lists stored forms from a target database and runs them without exposing design
mode. The new host reuses the existing DataEntry runtime component from
CSharpDB.Admin.Forms, with small opt-in parameters added so runtime-only hosts
can hide the designer action and provide a back link without changing default
Admin studio behavior.

The current range also includes a small Admin UI polish pass: the form designer
property inspector now renders selected control IDs with theme-aware styling,
the SQL query tab has a visible resizable splitter between editor and results,
and the visual query designer has a matching splitter for the generated SQL
preview versus results.

The final website pass also adds the Fulfillment Hub sample walkthrough blog
post, applies consistent tutorial code color-coding across the static docs,
updates the REST API reference to reflect daemon-hosted REST/gRPC, and refreshes
the v3.4 changelog plus roadmap entries.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Refactor / maintenance
• Tests only

Related Issues

No issue numbers were linked for this docs/site, sample, and forms-runtime
work. Included work in this PR:

• audited the current docs/ markdown tree against the published www site
• added source-reference HTML pages for the partially migrated long-form docs
• linked the curated pages to those full references and updated the sitemap
• removed high-confidence duplicated markdown files after link cleanup
• added the CSharpDB.Admin C# launcher blog post to the website
• added the samples/fulfillment-hub runnable sample with forms, reports,
  procedures, saved queries, pipelines, collections, and full-text search
• rewrote the Fulfillment Hub README into a guided operator walkthrough
• added the CSharpDB.Admin.Forms.Web runtime-only forms host
• updated CSharpDB.Admin.Forms runtime entry so the shared form runner can be
  hosted without a visible designer action
• fixed the form designer property inspector control ID rendering so it no
  longer relies on hard-to-read readonly input colors in dark theme
• added a resizable SQL editor/results splitter in the query tab
• added a resizable SQL preview/results splitter in the visual query designer

Testing

• dotnet build CSharpDB.slnx
• Relevant tests executed
• Failure-path tests executed (if applicable: cancellation, invalid/unsupported inputs, non-DbException paths)
• Manual verification performed (if applicable)

Validation performed for this PR:

• markdown-to-HTML content audit confirmed:
  • docs/architecture.md -> www/architecture-reference.html
  • docs/getting-started.md -> www/docs/getting-started-reference.html
  • docs/performance.md -> www/docs/performance-reference.html
  • docs/query-execution-pipeline.md -> www/docs/query-execution-pipeline.html
  • docs/sql-reference.md -> www/docs/sql-reference.html
  • docs/storage/README.md -> www/docs/storage-engine-reference.html
  • docs/roadmap.md -> www/roadmap-reference.html
  • docs/query-and-durable-write-performance/csharpdb-vs-sqlite-benchmarking-blog.md -> www/blog/csharpdb-vs-sqlite-benchmarking-reference.html
• coverage audit showed 100% heading coverage and 99.7-100% token overlap for
  the migrated source-reference set
• python -c "import xml.etree.ElementTree as ET; ET.parse('www/sitemap.xml')"
  passed after updating the sitemap
• repo scan found no remaining references to the deleted duplicated markdown
  files (cli.md, rest-api.md, mcp-server.md, internals.md,
  storage-inspector.md)
• dotnet run --project samples\fulfillment-hub\FulfillmentHubSample.csproj
  completed successfully and seeded the sample database with:
  • 3 forms
  • 3 reports
  • 5 procedures
  • 5 saved queries
  • 3 stored pipelines and 3 successful pipeline runs
  • 2 collections
  • the fts_ops_playbooks full-text index
• dotnet build src\CSharpDB.Admin.Forms.Web\CSharpDB.Admin.Forms.Web.csproj
  completed successfully
• dotnet build src\CSharpDB.Admin.Forms\CSharpDB.Admin.Forms.csproj
  completed successfully after the property inspector styling change
• dotnet build src\CSharpDB.Admin\CSharpDB.Admin.csproj -p:BaseOutputPath=C:\Users\maxim\source\Code\CSharpDB\artifacts\verify\
  completed successfully after the query tab and visual designer splitter
  changes
• Sequential unit-test run completed with 1644 passed, 0 failed, and 0
  skipped across:
  • CSharpDB.Admin.Forms.Tests
  • CSharpDB.Admin.Reports.Tests
  • CSharpDB.Api.Tests
  • CSharpDB.Cli.Tests
  • CSharpDB.Daemon.Tests
  • CSharpDB.Data.Tests
  • CSharpDB.EntityFrameworkCore.Tests
  • CSharpDB.Pipelines.Tests
  • CSharpDB.Tests
• node --check www\js\csharpdb.bundle.js passed after adding the static docs
  code highlighter
• browser smoke verification confirmed all tutorial code blocks are processed
  and the REST API reference renders with daemon-hosted REST wording
• dotnet run --project src\CSharpDB.Admin.Forms.Web\CSharpDB.Admin.Forms.Web.csproj -- --urls http://127.0.0.1:5095 --CSharpDB:DataSource=<fulfillment-hub-demo.db>
  started successfully
• HTTP verification against the new forms host confirmed:
  • / lists the seeded forms Order Workbench, Purchase Order Receiving,
    and Return Intake
  • /forms/orders-workbench returns 200
  • the runtime page still shows standard form actions such as Save and
    Delete
  • the runtime page does not expose the Edit Form designer action

Checklist

• I followed the project style and conventions.
• I updated docs for user-facing changes.
• I verified no sensitive data was added.

Notes for Reviewers

• The important semantic correction in this range is that the original
  docs/query-execution-pipeline.md content is no longer implicitly treated as
  if it were the same page as the shipped ETL pipelines guide. It now has its
  own source-reference route under www/docs/query-execution-pipeline.html.
• The shorter curated docs remain the primary public landing pages; the new
  source-reference pages exist to preserve the original long-form markdown
  material before deleting redundant copies from docs/.
• Only the high-confidence duplicated markdown files were removed in this pass.
  The remaining markdown files still need their own migration/verification work
  before they are safe to delete.
• The forms-only web host intentionally reuses the shared DataEntry runtime
  component rather than forking it into a separate codepath. The only shared
  component changes are opt-in runtime-hosting parameters; existing Admin
  behavior stays unchanged by default.
• The latest Admin UI fixes are narrow and local: one theme/readability fix in
  the form designer property inspector, one splitter for SQL mode, and one
  splitter for visual designer mode.
• The static website updates are documentation-only, except for the shared
  client-side highlighter in www/js/csharpdb.bundle.js; it uses the existing
  site token classes and does not add a new third-party dependency.