fix(claudecode): replace dots in project key encoding

[KuaaMU]

Fixes #842

Environment

• cc-connect version: v1.3.2 (19406df)
• OS: macOS Darwin 25.3.0 (arm64)
• Agent: Claude Code 2.1.91
• Platform: any (bug is in core encoding logic)

Root Cause

encodeClaudeProjectKey in agent/claudecode/claudecode.go replaces /, :, _, , ~ with - but does not replace . (dot).

Claude Code 2.1.91 does replace dots in its project key encoding. This means any workspace path containing a dot (e.g. /Users/yinglong.li/projects/myapp) produces a different key than what Claude Code writes to disk, causing findProjectDir to fail and /list to return 0 sessions.

Reproduction

1. Use a macOS account with a dot in the username (e.g. yinglong.li)
2. Start cc-connect with Claude Code agent
3. Run /list in the messaging platform
4. Expected: shows active sessions. Actual: returns 0 sessions.

Fix

Added . to the replacement set in encodeClaudeProjectKey, matching Claude Code 2.1.91 behavior.

Tests

go test ./agent/claudecode/ -run TestEncodeClaudeProjectKey -v

Added two new test cases:

• path with dots in username: /home/john.doe/projects/myapp → -home-john-doe-projects-myapp
• path with multiple dots: /home/j.doe/src/my.app → -home-j-doe-src-my-app

All 14 tests pass (12 existing + 2 new).

[chenhg5]

Thanks for the fix! This PR addresses the same issue as #820, which was submitted by @Re-TinyLin and has already been reviewed and approved. To avoid duplicate history in main, I'll defer to #820 for the merge. Closing in favor of #820.