feat(email): add attachment support for send and reply

[napoleond]

Add --attach flag (repeatable) to email send and reply commands. The CLI
reads local files, detects MIME type from extension, and base64-encodes
content before passing to the MCP tool. Inbox and search results now
display attachment metadata (filename, type, size) inline.

https://claude.ai/code/session_013ZfRLDGZ9mawSATTJ8ToQg

[github-actions]

AI Code Review

Recommendation: APPROVE (comment only — approval blocked by repo policy)

Summary

Adds a repeatable --attach flag to email send and email reply commands, reads local files with MIME-type detection and base64 encoding, and surfaces attachment metadata in inbox/search listings. Documentation in SKILL.md is thorough and accurate.

Actionable Feedback (2 items)

• email.ts:loadAttachments - No pre-read file size check. A large file will be fully loaded into memory before the server rejects it. Consider fs.statSync(resolved).size and fail fast if it exceeds the documented 7.5 MB raw limit.
• email.ts:checkInbox and searchEmails - The attachment display block is identical in both functions. Extracting it to a small helper would reduce duplication.

Code Quality

Clean implementation. loadAttachments correctly uses path.resolve and path.basename. The static MIME map covers common types with a sensible application/octet-stream fallback. getAllArgValues was already present in index.ts for similar repeated flags, so the wiring is consistent.

Security

No concerns. path.resolve normalises the user-supplied path before reading, preventing path-traversal issues. File content is base64-encoded before leaving the process.

Positive Notes

• Error handling on readFileSync is correct: catches, formats the message, and exits with code 1.
• SKILL.md documentation is complete: usage examples, MCP tool parameter table, and the 10 MB size-limit caveat are all present.
• The attachment count indicator in inbox/search gives a nice at-a-glance signal without being noisy.