Add database migration to merge findings

Merge nonconformities and continual_improvements tables into a
unified findings table with kind (NONCONFORMITY, OBSERVATION,
EXCEPTION), status, and priority enums. Create findings_audits
junction table for the many-to-many audit relationship.

The migration generates new FND-XXX reference IDs per organization,
migrates both live and snapshot records preserving source_id links,
and carries over audit associations to the junction table.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/coredata/migrations/20260315T100000Z.sql

@@ -0,0 +1,4 @@
+-- Add FINDINGS value to snapshots_type enum
+-- This must be in its own migration because PostgreSQL requires the new enum
+-- value to be committed before it can be used in DML statements.
+ALTER TYPE snapshots_type ADD VALUE IF NOT EXISTS 'FINDINGS';