fix: prevent dictionary false positives + add tunnel-doctor WSL/Go findings

transcript-fixer:
- Add common_words.py safety system (blocks common Chinese words from dictionary)
- Add --audit command to scan existing dictionary for risky rules
- Add --force flag to override safety checks explicitly
- Fix substring corruption (产线数据→产线束据, 现金流→现现金流)
- Unified position-aware replacement with _already_corrected() check
- 69 tests covering all production false positive scenarios

tunnel-doctor:
- Add Step 5A: Tailscale SSH proxy silent failure on WSL
- Add Step 5B: App Store vs Standalone Tailscale on macOS
- Add Go net/http NO_PROXY CIDR incompatibility warning
- Add utun interface identification (MTU 1280=Tailscale, 4064=Shadowrocket)
- Fix "Four→Five Conflict Layers" inconsistency in reference doc
- Add complete working Shadowrocket config reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

transcript-fixer/scripts/cli/argument_parser.py

@@ -37,12 +37,24 @@ def create_argument_parser() -> argparse.ArgumentParser:
         dest="add_correction",
         help="Add correction"
     )
+    parser.add_argument(
+        "--force",
+        action="store_true",
+        default=False,
+        help="Force --add even when safety checks detect risks (common word, substring collision)"
+    )
     parser.add_argument(
         "--list",
         action="store_true",
         dest="list_corrections",
         help="List all corrections"
     )
+    parser.add_argument(
+        "--audit",
+        action="store_true",
+        dest="audit_dictionary",
+        help="Audit all active corrections for false positive risks (common words, short text, substring collisions)"
+    )
 
     # Correction workflow
     parser.add_argument(