Consolidate backend: drop vendored APwhy, converge on goose + sqlc

Phase 0 cleanup verified end-to-end:

- Delete vendored APwhy runtime (cmd/apwhy, internal/apwhy) and the
  unwired copy (internal/api/server.go + static bundle + cloned
  internal/{storage,analytics,auth,rbac}) — ~7.5k lines of dead code.
- Keep Containr's native internal/gateway; move APwhy management
  routes under /api/v1/gateway/* so they stop colliding with the
  native /services paths. Fix handlers against the real schema:
  UUID ids via RETURNING, integer enabled flags, plan validation,
  service validate endpoint, unique-violation mapping.
- Port agents.go off GORM onto sqlc (sqlc/queries/agents.sql);
  drop gorm dependencies; fix sqlc schema drift (services.environment_id).
- Replace the SELECT 1 goose baseline with the real consolidated
  schema (52 tables) minus APwhy's parallel auth/RBAC objects;
  idempotent via IF NOT EXISTS / OR REPLACE / guarded DO blocks so it
  replays cleanly over legacy installs. Add a drop migration for the
  dead objects and delete the legacy filename-tracked migrations/
  loader, directory, and Dockerfile copy. Verified via cmd/migrate:
  fresh install 53 tables, legacy upgrade clean to 20260917000000.
- Canvas: add invisible React Flow handles to ServiceNode so inferred
  auto-connections stop emitting warning #008.
- Remove reactflow dep (superseded by @xyflow/react), test harness
  cmds, and legacy 0001_init.sql backups.

Authored By: TDvorak <[email protected]>

app/backend/Dockerfile

@@ -32,7 +32,6 @@ RUN addgroup -g 1001 -S appgroup && \
 WORKDIR /app
 
 COPY --from=go-builder /app/main ./main
-COPY --from=go-builder /app/migrations ./migrations
 COPY --from=go-builder /app/migrations_goose ./migrations_goose
 COPY --from=auth-builder /auth ./auth