style(rmi-backend): complete lint cleanup — 1175→0 ruff errors

- Fix 71 invalid-syntax files (class-body newline-broken assignments)
- Add from/None chain to 307 B904 raise-without-from sites
- Add B008 ignore to ruff.toml (already in pyproject.toml)
- Noqa F401 on __init__.py re-exports (137 sites)
- Noqa E402 on deferred imports (63 sites)
- Bulk-add stdlib/FastAPI/project imports for F821 (127 sites)
- Replace ×→x, –→-, …→... in docstrings (4093 chars)
- Manual refactor of 5 SIM103/SIM116 patterns

Tests: 791 passed (66 deselected due to pre-existing Redis issues in test_rag.py)
Co-authored-by: opencode <opencode@rugmunch.io>

scripts/ops/qdrant_audit.py

@@ -1,11 +1,11 @@
 #!/usr/bin/env python3
 """Qdrant collection audit + cleanup for test_col_* artifacts.
 
-T15 (G14 FIX) — Qdrant accumulates test_col_* collections from integration
+T15 (G14 FIX) - Qdrant accumulates test_col_* collections from integration
 tests that forget to clean up. This script audits and cleans them.
 
 Usage:
-    # Audit only (safe — no changes):
+    # Audit only (safe - no changes):
     python scripts/ops/qdrant_audit.py
     python scripts/ops/qdrant_audit.py --audit-only
 
@@ -68,7 +68,7 @@ def main() -> int:
     p.add_argument(
         "--audit-only",
         action="store_true",
-        help="Only audit — never delete anything",
+        help="Only audit - never delete anything",
     )
     p.add_argument(
         "--cleanup",
@@ -102,7 +102,7 @@ def main() -> int:
     print(f"  Test artifacts (test_col_*): {len(test_like)}")
 
     if not test_like:
-        print("\nCLEAN — zero test_col_* artifacts.")
+        print("\nCLEAN - zero test_col_* artifacts.")
         return 0
 
     print("\n--- Test artifacts detail ---")