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>

app/bundle_detector.py

@@ -1,5 +1,5 @@
 """
-Bundle Detection Engine — Atomic block co-occurrence analysis.
+Bundle Detection Engine - Atomic block co-occurrence analysis.
 Detects Jito bundles, Flashbots bundles, and coordinated launches.
 Implements: atomic-block grouping, common funder, temporal clustering,
 distribution anomaly detection, holder concentration scoring.
@@ -174,7 +174,7 @@ class BundleDetector:
             result.temporal_score = 0.3
 
     def _distribution_anomaly_signal(self, result: BundleDetection, holders: list[dict]):
-        """Check for flat/rounded amounts — hallmark of bundled distribution."""
+        """Check for flat/rounded amounts - hallmark of bundled distribution."""
         amounts = []
         for h in holders:
             amt = h.get("amount", 0)