docs: document the 1.52.0 feature wave (reference, concepts, dagster)

[hugocorreia90]

PR 1 of a 3-part sweep documenting the engine 1.52.0 feature wave, which shipped after the last docs overhaul and was almost entirely undocumented (found by a coverage audit). This PR covers the reference, concept, and dagster pages; a follow-up covers discovery/positioning pages, and a third adds runnable POCs.

Correctness fixes (these were wrong on main)

• guides/migrate-from-dbt.md — removed the stale claim that emitted [[test]] blocks "aren't yet wired into rocky test execution." They execute as of engine-v1.52.0 (feat(engine): execute fixture-driven unit tests in rocky test #899). The still-true "CSV / SQL fixtures deferred" clause is preserved.
• concepts/testing.md — the failures example showed the obsolete positional-tuple shape; it's now [{name, error}] objects (fix: address self-review findings across engine, rocky-sdk, and dagster #924), matching the generated TestOutput schema and the other reference pages.

Reference

• model-format.md — five new sidecar-block sections: [[surrogate_key]], [[tests]], [[use_test]], [[test]], [columns.<name>], plus group/[args] rows in the Fields table. Per-column docs are scoped to rocky catalog --output json (not the rocky docs HTML, which has no column introspection).
• cli.md + commands/modeling.md — the new rocky emit-sql verb (+ backfilled rocky catalog), the rocky test unit_tests summary, the per-column description in catalog output, and a populated rocky compile models_detail example with a tags object.
• json-output.md, configuration.md, glossary.md — unit_tests/tags/failures-shape notes, a config-groups cross-reference, and surrogate-key + config-group glossary entries.

Concepts & Dagster

• testing.md (declarative + unit-test sections), data-quality-checks.md ([[test]] vs [[tests]] callout), sql-generation.md (surrogate-key SQL + dbt_utils parity), schema-patterns.md (config-groups distinction).
• dagster/{translator,derived-models,types,resource} — the model-tag projection (get_model_tags), ModelDetail.tags, and the TestOutput/CiOutput aliases.

How this was produced & verified

15 files, one agent per file, each draft adversarially verified against the source (accuracy + de-AI prose standard), then a cross-link/terminology sweep. The verify pass caught real issues — e.g. a draft wrongly claimed rocky catalog has no JSON mode (it does; emit-sql doesn't), and the compile example's signals string was checked verbatim against the live dagster fixture. +826 / −10 across 15 files (deletions are the two correctness rewrites + a couple of hedge phrasings).

• astro build green (89 pages, no frontmatter/MDX/link errors).
• GOLD/proprietary grep clean — the only gold matches are medallion-layer (schema: "gold", tier: "gold"), consistent with the existing bronze-layer/silver-layer docs.

🤖 Generated with Claude Code