What does this PR do?

Pre-compiles regex patterns used for markdown stripping in TTS and messaging functions, eliminating repeated regex compilation overhead on every function call. This improves performance for voice mode and SMS sending.

Related Issue

N/A (performance optimization)

Type of Change

• ♻️ Refactor (no behavior change)

Changes Made

• tools/send_message_tool.py: Pre-compiled 9 markdown stripping regex patterns into _MD_STRIP_PATTERNS tuple at module load
• tools/tts_tool.py: Pre-compiled 10 markdown stripping regex patterns into _MD_STRIP_PATTERNS tuple at module load
• cli.py: Pre-compiled 10 markdown stripping regex patterns into _TTS_MD_PATTERNS tuple at module load

Before: Each function called re.sub() 9-10 times sequentially, recompiling patterns on every invocation.

After: Patterns pre-compiled once at import time in a tuple, then applied in a loop.

How to Test

1. Run syntax checks:

   python3 -m py_compile tools/send_message_tool.py tools/tts_tool.py cli.py

2. Verify imports work:

   python3 -c "from tools.send_message_tool import _MD_STRIP_PATTERNS; print('OK')"
   python3 -c "from tools.tts_tool import _MD_STRIP_PATTERNS; print('OK')"
   python3 -c "from cli import _TTS_MD_PATTERNS; print('OK')"

3. Test pattern correctness:

   import re
   _MD_STRIP_PATTERNS = (
       (re.compile(r'\*\*(.+?)\*\*'), r'\1'),
       (re.compile(r'\*(.+?)\*'), r'\1'),
       (re.compile(r'__(.+?)__'), r'\1'),
       (re.compile(r'_(.+?)_'), r'\1'),
       (re.compile(r'```[a-z]*\n?'), ''),
       (re.compile(r'`(.+?)`'), r'\1'),
       (re.compile(r'^#{1,6}\s+', flags=re.MULTILINE), ''),
       (re.compile(r'\[([^\]]+)\]\([^\)]+\)'), r'\1'),
       (re.compile(r'\n{3,}'), '\n\n'),
   )
   test = '**bold** and *italic* and [link](http://example.com)'
   for pattern, replacement in _MD_STRIP_PATTERNS:
       test = pattern.sub(replacement, test)
   assert test == 'bold and italic and link'

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits
• I've searched for existing PRs to ensure this isn't a duplicate
• My PR contains only changes related to this optimization
• Syntax validation passes
• Patterns tested for correctness

Documentation & Housekeeping

• N/A - no documentation changes needed (behavior unchanged)
• N/A - no config changes
• N/A - no architecture changes
• N/A - no tool schema changes