ci: reject leading ticket tags in commit headers (release-please parseability)

[robsongajunior]

Summary

• release-please cannot parse a squash title that starts with a bracket ticket tag: fix: use @aziontech/theme/animations imports; move vue-tsc to devDependencies #804 merged as [NO-ISSUE] fix: … and silently released nothing (run 30270134693 — commit could not be parsed … unexpected token ' ' at 1:11). Its parser is not configurable (the old .releaserc parserOpts died with ci: replace semantic-release with release-please (Release PR model) #798).
• New convention: the header starts with the bare type; a ticket tag goes at the start of the subject only when a real ticket exists — fix(webkit): [ENG-1234] subject. No ticket → no tag: [NO-ISSUE] is dead characters (100-char budget, changelogs) and is rejected.
• commitlint.config.js now matches release-please's parser exactly, with two inline rules guarding the migration: header-no-leading-ticket (old leading-tag form → actionable error) and subject-ticket-tag (well-formed [ABC-123] only; [NO-ISSUE] → "omit the tag entirely").

Notes

• Docs synced in the same PR (four-surface rule): CONTRIBUTING.md § Message shape / Local enforcement, DOC_LINTS.md §10 (header anatomy + ❌/✅ examples), and the /open-pr + /create-branch prompts. Every example was verified against the real commitlint config.
• CONTRIBUTING.md § Releasing also corrected: it still described semantic-release; it now documents the release-please Release PR model (ci: replace semantic-release with release-please (Release PR model) #798).
• No release from this PR (ci/docs). Old-form commits were already release-inert — they now fail loudly at commit time instead. The release missed by fix: use @aziontech/theme/animations imports; move vue-tsc to devDependencies #804 will be recovered separately (release-please BEGIN_COMMIT_OVERRIDE retrofit).
• Also exempts generated **/CHANGELOG.md from the Prettier gate (.prettierignore, same precedent as catalog.json): release-please commits changelogs via the GitHub API in its own markdown style (* bullets), which was failing the Linting & Formatting check on Release PR chore: release main #810. Verified against the real release-please--branches--main content.
• No new dependencies.