[ai][docs] vocabulary plan: migrations declare and test their delete paths

[ddol]

Purpose

Carry the two still-valid items from the retired SQLite schema v2 freeze plan into the two-phase vocabulary programme (#631). That plan was removed in 510415a, before #559 merged. A review against #631 found nothing else in it that survives the shared-VRLOG design (VRLOG as the observation authority, SQLite as a rebuildable catalogue), so the plan itself is not restored.

Changes

• The "000055 pattern" bullet in the vocabulary plan now also requires every new or rebuilt foreign key to declare its ON DELETE action and have a delete-path test, with PRAGMA foreign_key_check after the move. A rename keeps today's cascades without anyone noticing.
• P2-B (clips and labels) acceptance:
  • Deleting a clip has a declared, tested effect on its labels. Today lidar_replay_annotations.replay_case_id is ON DELETE CASCADE, so deleting a clip deletes reviewed labels, which no recording can rebuild.
  • Nothing writes pcap_file once it is a read-only projection.
• P2-F (sites and surveys) acceptance: deleting a site has a declared, tested effect on its deployments. Today site_config_periods.site_id is ON DELETE CASCADE.

Validation

• Both cascades were checked in internal/db/schema.sql (lines 451 and 966).
• The rest of the retired plan is covered by existing work, so it is not carried over:
  • startup refuses a dirty migration (migrate.go);
  • schema drift is checked (schema_consistency_test.go, P1-B);
  • rejected rows are quarantined (migration_rejects);
  • aliases expire (P1-A/P2-G);
  • foreign_key_check already runs in migration_055_test.go.
• Prettier, backtick-path and plan-hygiene checks pass.

Checklist

• Uses British English spelling/wording where applicable.
• Design is confirmed and aligns with DESIGN.md.
• Any maths/derived values are valid and up to date.
• Version has been bumped where required. (Not required: documentation only.)
• Documentation is up to date.
• README.md is up to date. (Not affected.)
• docs/DEVLOG.md is up to date. (Plan acceptance items only.)

🤖 Generated with Claude Code

[Copilot]

Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.