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/__init__.py

@@ -9,6 +9,7 @@ This module contains command handlers and argument parsing:
 from .commands import (
     cmd_init,
     cmd_add_correction,
+    cmd_audit,
     cmd_list_corrections,
     cmd_run_correction,
     cmd_review_learned,
@@ -25,6 +26,7 @@ from .argument_parser import create_argument_parser
 __all__ = [
     'cmd_init',
     'cmd_add_correction',
+    'cmd_audit',
     'cmd_list_corrections',
     'cmd_run_correction',
     'cmd_review_learned',