feat: cost schema the production snapshot doesn't cover via the synthesizer

[veksen]

Goal

The analyzer side of Production Statistics (Site#3587, ADR 0007). Makes the core synthesizer actually run on the connected and CI costing paths, so a table the production snapshot has never seen is costed with an extrapolated row count instead of the flat 10M default.

Blocked on @query-doctor/core@0.16.0. It publishes when Site#3587 merges to staging. Until then npm install can't resolve the range and CI is red — expected, and the only thing left blocking this branch.

What

Before, QueryOptimizer.setStatistics built Statistics without the current schema, so a table outside the snapshot's coverage fell to the default and an unindexed scan over it looked free. After, the schema is passed in, so those tables are sized by the synthesizer — foreign-key graph, then shape class, then database median — with column stats inferred from type and constraints.

Both the connected and CI paths already thread the schema through onSuccessfulSync → optimizer.start, so one wiring change covers both.

How

• query-optimizer.ts — pass schema as the fifth Statistics argument (the only new Statistics in this repo), and add a syntheticTables getter mirroring computedStats / ownMetadata.
• reporter.ts / runner.ts — plumb the synthesized-table set onto ReportContext.modeledTables.
• package.json — @query-doctor/core to ^0.16.0, the minor that adds the currentSchema constructor argument and the syntheticTables getter.

The push path is unaffected: it sends ownMetadata (remote.ts:392), and synthesized numbers live only in computedStats. A modeled row count can't reach the stored snapshot.

Deferred to a follow-up

Rendering the "modeled, not verified" banner in the PR comment — template, buildViewModel, snapshot regen. Left until core publishes so the template and snapshot tests are validated rather than written blind. That banner is the half of Site#3420 a developer actually sees, so this branch does not close it on its own.

Sequencing

1. Site#3587 → staging → core publishes 0.16.0.
2. Here: npm install to sync the lockfile (it still carries ^0.15.0 from main), CI goes green.
3. Then the comment-render follow-up.

Tests

query-optimizer-synthesis.test.ts covers the wiring: that setStatistics forwards the schema, and that syntheticTables reports tables the snapshot doesn't cover. It runs against a testcontainer and goes green once core publishes.

[github-actions]

Query Doctor Analysis

3 queries analyzed

0 regressed · 0 improved · 0 new · 0 removed

2 pre-existing issues

• SELECT "guests"."id", "guests"."session_id", "guests"."username", "guests"."avatar_path", "guests"."color", "guests"."side", "guests"."audio_recording_path", "guests"."audio_recording_public", "gue...
  index assets(event_id, inserted_at desc)
  cost 31,003,449 → 1,498 (100% reduction)
• SELECT * FROM guest_ip_addresses WHERE ip_address = '127.0.0.1';
  index guest_ip_addresses(ip_address)
  cost 154,402 → 8 (100% reduction)

_{Using assumed statistics (10000000 rows/table). For better results, sync production stats.}

_{More detail → get_ci_run({ runId: "019fa469-27b6-769f-8505-d50e1bd3fdec" }) · view run · docs}