postgres-first-target-runbook.md predates most of the current PostgreSQL collector set; section 12 denies features that shipped #3247

Split out of #3239, which fixed only step 1's grant story (the pg_read_file log-reader grants). The rest of the runbook has drifted a long way behind the code and needs a verification pass of its own — it is the onboarding document, and several of its confident claims are now false in the direction that makes a working install look broken (or the product look smaller than it is).

Measured against dev today:

• Step 3's pre-flight table tops out at "9 PostgreSQL collectors" and step 7's cadence table lists 13. The dispatch table in DarlingWorker registers 27 pg_* collectors. The per-target applies/skipped table and the first-row/first-meaningful-read table both need re-deriving from CollectorCatalog.
• Step 5's proof line says "Postgres store ready (schema v68)"; the store is at v114+ now. The number is presented as the thing to verify, so a reader following the proof point exactly concludes their store migrated wrong.
• Section 12 ("What this does not cover, because it does not exist yet") denies shipped features:
  • "Plan capture. No PostgreSQL equivalent in the store." — collect.pg_plan_capture shipped in Store PostgreSQL plans: query_plan_dim is built for SQL Server plan XML, and PostgreSQL plans are JSON #2566 (self-hosted) and PostgreSQL has no execution plan capture, which is where a DBM comparison is lost #2538/pg_deadlocks: wire the missing Aurora/RDS dispatch branch (100% fleet failure) #2692 (Aurora/RDS via the log API), plus pg_plan_capture_readiness (Detect whether PostgreSQL plans can be captured at all, and say so — the shippable first slice of #2538 #2564).
  • "Blocking chains. Designed, not built" — pg_blocking is built, dispatched, and has get_pg_blocking.
  • "Scheduled analysis. Still SQL-Server-shaped" — DarlingWorker carries a PostgreSQL analysis_state path with its own tool list.
  • "The Viewer. ... still SQL-Server-shaped." — ViewerServerTab.Postgres.cs / ViewerDataService.Postgres.cs exist.
• Step 8's MCP tool table lists 13 get_pg_* tools; DarlingWebEndpoints registers more (deadlocks, plan capture readiness, session states, column stats, database stats...). Needs re-deriving rather than appending.

The runbook's own header says "correct this file from what you actually see", so the right shape for this fix is a live re-run against a self-hosted target and an Aurora/RDS target, not a desk edit — which is why it is an issue rather than a rider on #3239.