feat(signals): classify automation and CI toolchain config in path-matchers

[jason020818]

Summary

Extends isConfigFile / classifyChangedFile so slop signals stop miscounting common automation and hosted-CI config as uncategorized source effort (#561).

New config recognition:

• Dependency automation: renovate.json, dependabot.yml
• Toolchain pins: .tool-versions, mise.toml
• Git hooks: lefthook.yml / .lefthook.yaml, .pre-commit-config.yaml
• Hosted CI: .gitlab-ci.yml, azure-pipelines.yml, .github/workflows/*.yml, .circleci/config.yml
• Protobuf codegen: buf.yaml, buf.gen.yaml

Path-only, deterministic, full unit coverage + negative cases.

Test plan

• npm test -- test/unit/path-matchers.test.ts

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.39%. Comparing base (a356441) to head (a5d5558).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1261   +/-   ##
=======================================
  Coverage   95.39%   95.39%           
=======================================
  Files         193      193           
  Lines       20929    20932    +3     
  Branches     7564     7566    +2     
=======================================
+ Hits        19966    19969    +3     
  Misses        383      383           
  Partials      580      580           

Files with missing lines	Coverage Δ
src/signals/path-matchers.ts	100.00% <100.00%> (ø)

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[JSONbored]

This is the earlier of the two path-matcher PRs and it's correct — workflow/circleci/dependabot regexes plus the common toolchain basenames, with a real "renovate-like source names aren't config" guard. It wins the tiebreak over the later #1422 by being the original, not because either is "better." It's a jaso0n0818 fork so I won't touch it — your call to take it; if you do, #1422's extra lockfile/config entries can be folded in after.