fix(github): require a handle boundary after @gittensory in mention parsing

[galuis116]

Summary

Fixes #1344.

parseGittensoryMentionCommand matched the bot handle with no boundary after @gittensory, so the handle matched as a prefix of a longer GitHub username. A comment mentioning a different account such as @gittensory-bot or @gittensory2 was parsed as a bare @gittensory help, and the only caller then posted an unsolicited help reply on that thread.

What changed

• Added a (?![\w-]) boundary after @gittensory in the mention regex. GitHub usernames are word characters + hyphen, so the lookahead rejects @gittensory-bot / @gittensory2 / @gittensorybot while still matching bare @gittensory, @gittensory <command>, and punctuation boundaries.

Scope

• Conventional Commit title.
• Focused; no unrelated changes.
• Follows CONTRIBUTING.md; no site//CNAME/VitePress.
• Linked issue ([Bug]: @gittensory mention regex matches longer handles (@gittensory-bot) as a bare command #1344).

Validation

• git diff --check
• npm run typecheck
• npm run test:coverage locally (github-commands suite green); the changed regex line is fully covered, including the now-rejected longer-handle cases and the retained positive cases.
• npm audit --audit-level=moderate
• New unit tests for @gittensory-bot / @gittensory2 / @gittensorybot → null, and a punctuation-boundary positive case.

If any required check was skipped, explain why:

• OpenAPI/types unchanged — internal command-parsing logic only.

Safety

• No secrets, wallets, hotkeys, PATs, trust scores, or private evidence exposed.
• Public text sanitized and low-noise.
• GitHub App command-parsing change includes negative-path tests (mentions of other handles now correctly ignored).
• API/OpenAPI/MCP behavior unchanged.
• No UI changes.
• No changelog edit.

Notes

• Confined to the regex in parseGittensoryMentionCommand (src/github/commands.ts); no schema, migration, or binding changes.

[superagent-security]

Superagent did not find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.25%. Comparing base (2e99233) to head (52d015e).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1345   +/-   ##
=======================================
  Coverage   95.25%   95.25%           
=======================================
  Files         188      188           
  Lines       20314    20314           
  Branches     7319     7319           
=======================================
  Hits        19350    19350           
  Misses        378      378           
  Partials      586      586           

Files with missing lines	Coverage Δ
src/github/commands.ts	97.44% <100.00%> (ø)

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