feat(regex): detect %-style (LaTeX/Matlab) comments

[Yuki-zik]

Summary

Adds % to the default taskvision.regex.regex comment-prefix alternation so TODO/FIXME (and other tags) are detected in %-style comments used by LaTeX, Matlab and Erlang (e.g. % TODO, % FIXME).

Root cause

The default detection regex lacked % in its comment-prefix group:

(//|#|<!--|;|/\*|^|^[ \t]*(-|\d+.))\s*($TAGS)

src/config.js reads this package.json default (no hardcoded fallback), so %-prefixed comments were never matched.

Changes

• package.json — added % to the taskvision.regex.regex default → (//|#|<!--|;|/\*|%|^|^[ \t]*(-|\d+.))\s*($TAGS).
• src/extension.js — synced the "reset regex to default" command (markdown-support popup) with the new default so it doesn't undo the fix.
• reproduce_issue_v9.js — synced the hardcoded default-regex stub for consistency.
• test/tests.js — added a QUnit case asserting % TODO fix this / % FIXME are detected and that // / # still work.
• CHANGELOG.md — added an Unreleased entry.
• agent/tasks.md, agent/timeline.md — governance audit trail per repo AGENTS.md.

Verification

• npm test → 120 passing, 0 failing (was 119; new %-comment case passes)
• npm run webpack → build succeeded
• package.json validated as valid JSON with the updated default

Fixes #3

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