Problem

_extract_attachments() in mcp_serve.py uses a single-token regex
(MEDIA:\s*(\S+)) to extract attachment paths. This truncates or
malforms any path that contains spaces or is wrapped in quotes/backticks:

MEDIA: "C:\Users\\Desktop\my image.png"   → only captures `"C:\Users\\Desktop\my`
MEDIA: '/tmp/my image.png'                      → only captures `'/tmp/my`

This breaks attachments_fetch for valid Hermes outputs, especially on
Windows where file paths commonly include spaces.

This is distinct from the earlier fix in gateway/platforms/base.py:
the gateway path extraction was already hardened there, but the MCP
bridge still had the older, narrower parser.

What changed

Updated mcp_serve.py so _extract_attachments() no longer relies on
the single-token MEDIA:\s*(\S+) pattern. It now accepts:

• Quoted paths ("..." and '...')
• Backticked paths (`...`)
• Unix absolute and tilde paths with spaces
• Windows drive-letter paths with spaces

Extracted paths are normalized by trimming wrapping quotes/backticks and
trailing punctuation before being returned.

Why it matters

• Real behavior bug, not a refactor.
• Small and isolated to the MCP bridge.
• Improves Windows compatibility.
• Closes a consistency gap between gateway delivery parsing and MCP
  attachment parsing.

Tests

Added regression coverage in tests/test_mcp_serve.py:

• Quoted Unix path with spaces: MEDIA: "/tmp/my image.png"
• Quoted Windows path with spaces: MEDIA: "C:\Users\\Desktop\my image.png"
• Backticked path: MEDIA: `/tmp/out file.mp3`
• Trailing punctuation boundary: MEDIA: "/tmp/out.png", done
• Existing simple-path behavior unchanged

Verification:

python -m pytest tests/test_mcp_serve.py -q
# Result: 44 passed, 39 skipped

Manual verification

1. Call _extract_attachments() on text containing quoted MEDIA: paths
   with spaces and verify the full path is returned.
2. Confirm existing plain MEDIA: /tmp/out.png behavior still works.
3. Optionally run hermes mcp serve and verify attachments_fetch
   returns the full path for a message containing a quoted MEDIA: tag.

Files changed

• mcp_serve.py — updated _extract_attachments() parser
• tests/test_mcp_serve.py — added regression tests