Use-Case-Mapping-Filter für Master Controls + Mapper-Präzisionsfix

Phase 2: Live-Filter an /sdk/master-controls (Use Case, Quell-Regulierung,
Verifikations-Methode, Coverage, Primärzweck-Toggle, category via Member-EXISTS).
API mit EXISTS-Filtern + gecachten Meta-Counts in master-controls/route.ts.

Phase A: neue UseCase telekommunikation + Fix der Impressum-Fehlrouten im
Register (TKG/AT-TKG->telekommunikation, telemedien->dse, GewO->handelsrecht);
echte Impressum-Quellen (TMG/Mediengesetz) bleiben impressum. Deterministischer
Seed aus source_regulation; Tests grün.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend-compliance/scripts/classify_mc_use_cases.py

@@ -125,7 +125,7 @@ async def run_seed(conn, limit: int = 0) -> dict:
     await conn.execute(
         """INSERT INTO compliance.mc_use_case_sync_state
            (registry_hash, stage, total_mappings, mcs_classified)
-           VALUES ($1,'seed_source_regulation',$2,$3)""",
+           VALUES ($1,'seed_regulation',$2,$3)""",
         reg.registry_hash(), total, n_mc)
     return {"mcs_mapped": n_mc, "regulation_rows": n_reg,
             "use_case_rows": n_uc, "verification_rows": n_v}