Bug 2026200 - Migrate code-review CI from all tasks defined in .taskcluster.yml to taskgraph

[JohanLorenzo]

Summary

• Replaces the hand-crafted v1 .taskcluster.yml with a taskgraph-based setup
• Adds in-tree Docker images (python, taskboot, node) for all CI tasks
• All tasks consolidated to firefox-ci (previously split between firefox-ci and community-tc)
• Implements lint, test, frontend, build, deploy, hook, and release kinds

Dependencies

Requires mozilla-releng/fxci-config#882 to add github-taskgraph: true and the code-analysis-{1,3}/decision worker pool for the code-review project.

Merge order

1. Merge Bug 2026200 - Grant code-review the ability to use taskgraph mozilla-releng/fxci-config#882 ✅ (merged, deployed to production)
2. Verify this PR on staging ✅ (all 13 tasks green)
3. Verify this PR on production (Firefox CI) ✅ — see below
4. Merge this PR

Verification

Staging

All commits verified end-to-end on staging via JohanLorenzo/code-review fork (PR: JohanLorenzo#1). See previous PR description revisions for full staging task links and log excerpts.

Production (Firefox CI) ✅

PR push event on mozilla/code-review — decision task ES3EHSHQQFi8SEX2iePYtw. All 9 tasks completed.

• lint-pre-commit ✅

  codespell...............................................................Passed
  taskcluster_yml.........................................................Passed
  Check for useless excludes..............................................Passed
  

• test-bot ✅

  136 passed, 173 warnings in 10.24s
  

• test-backend ✅

  Ran 38 tests in 0.850s
  

• test-integration ✅

  2 passed, 1 warning in 0.48s
  

• frontend-build ✅

  webpack 5.105.0 compiled successfully in 12024 ms
  

• build-bot ✅

  INFO:taskboot.docker:Built image .../mozilla/code-review:125b3b4..., .../mozilla/code-review:dev
  INFO:taskboot.docker:Saving image ... to /builds/worker/artifacts/bot.tar
  

• build-backend ✅

  INFO:taskboot.docker:Built image .../mozilla/code-review:125b3b4..., .../mozilla/code-review:dev
  INFO:taskboot.docker:Saving image ... to /builds/worker/artifacts/backend.tar
  

• build-integration ✅

  INFO:taskboot.docker:Built image .../mozilla/code-review:integration-125b3b4..., .../mozilla/code-review:integration-dev
  INFO:taskboot.docker:Saving image ... to /builds/worker/artifacts/integration.tar