Add external_ids, place_status, and user_verified fields

[koinsaari]

Summary

Schema prerequisites for the ingestion service — must be in place before inwheel-ingestion starts writing to the API.

Changes

Migration 000006

• places.external_ids JSONB — stores identifiers from external sources keyed by source name (e.g. {"osm": "node/123456"}). Used by the ingestion service to find existing places during OSM diff processing without matching on coordinates or name. GIN index for fast JSONB lookups.
• places.status place_status — enum active | closed | osm_removed. Protects user-contributed accessibility data when OSM removes a place: instead of hard-deleting, the ingestion service sets osm_removed and keeps the record.
• accessibility_profiles.user_verified BOOLEAN DEFAULT FALSE — set to true when a human user explicitly submits accessibility data. The ingestion service checks this before overwriting a profile with automated data.

Models

• PlaceStatus type with active, closed, osm_removed constants
• ExternalIDs custom JSONB map type (same Scan/Value pattern as PlaceTags)
• ExternalIDs and Status fields on Place
• UserVerified field on AccessibilityProfile

OpenAPI

• PlaceStatus enum schema
• external_ids (read/write) and status (readOnly) on Place
• user_verified (readOnly) on AccessibilityProfile
• Regenerated server.gen.go

All new columns have safe defaults — no existing data or tests break.

Closes #53

[claude]

Claude finished @koinsaari's task in 1m 19s —— View job

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Review complete

• Read changed files
• Check if previous bug (missing gorm:"default:active") was fixed
• Check for any new must-fix issues
• Post review summary

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The previously flagged bug is fixed: pkg/models/place.go:96 now has gorm:"type:place_status;default:active", so GORM will skip the zero-value field on INSERT and let the DB default kick in rather than sending an invalid '' to the enum column.

No other must-fix issues found. The migration order is correct (type created before column, column dropped before type in the down migration), ExternalIDs correctly returns SQL NULL for nil maps on a nullable column, and UserVerified bool requires no GORM default tag since the DB has DEFAULT FALSE and GORM v2 Create includes zero values explicitly.

PR looks good to merge.