Sweeps internal/services + internal/handlers + internal/models to use
the new proceeding codes landed by mig 096. Stable Code* constants
live in internal/services/proceeding_mapping.go so a future rename
needs to touch one file.
Substantive changes:
- proceeding_mapping.go gains ResolveCounterclaimRouting() — the
cascade resolver that routes upc.ccr.cfi (illustrative peer) back
to upc.inf.cfi with with_ccr=true as default flag (design doc S1).
- deadline_search_service.go forum-bucket map updated; upc.ccr.cfi
added to upc_cfi since it is a CFI peer.
- project_service.go CreateCounterclaim default lookup parameterised
so the SQL string carries the constant, not a literal.
- proceeding_codes_shape_test.go: new file. Validates the shape
regex standalone (always runs) and walks live DB rows asserting
every active fristenrechner row matches the new shape + every
stable Code* constant resolves to exactly one active row.
Comments and test fixtures throughout the Go tree updated to the
new shape. Tests pass under `go test ./internal/... -short`.
