ci: remove GitHub mirror workflows and dead Gitea manual workflows

Gitea (git.copse.top) is the only CI/CD control plane; GitHub is a
read-only mirror whose Actions are being disabled in repository settings.

- Delete all 11 `.github/workflows/*.yml` (stale copies of the old design).
- Delete unused Gitea manual workflows `ci.yml`, `test.yml`,
  `publish-pypi.yml`, `apply-supabase-profile-migrations.yml`
  (0-1 historical runs, no remaining target).
- Fold the full `python -m pytest` tree and `tests/run_all.py` into
  `release-quality-gate.yml`, which previously only ran the curated
  release profile; update the `run_quality_gate.py` comment accordingly.
- Port `reset-staging-account.yml` to Gitea: `runs-on: xiaoxin`, bounded
  exact-SHA checkout, `refs/heads/staging` only, `staging-mutation`
  concurrency, same email/confirmation/host/port/user/path assertions.
- Repoint frontend workflow tests at `.gitea/workflows/`, drop the
  GitHub-only assertions, add coverage for the new reset workflow, and
  remove `tests/test_supabase_profile_migration_workflow.py`.
- Update AGENTS.md §6.8, README.md, and deploy/README.md to the current
  production/mirror facts and document the staging account reset.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VawU7Xfd5jS9wUEXz1XYmS

scripts/run_quality_gate.py

@@ -59,9 +59,10 @@ CORE_PYTEST_TARGETS = [
     # Staging quick profile never runs `tests/` wholesale. A distinguish probe
     # with empty mapping or non-positive gain must fail this gate (BUG-393).
     "tests/test_candidate_discriminator_contract.py",
-    # Auto staging gate is `--profile quick`. `test.yml` / `ci.yml` run the
-    # full pytest tree but are workflow_dispatch only, so a stale window_scan
-    # assertion in this glob stayed red on origin/staging until listed here.
+    # Auto staging gate is `--profile quick`. The full pytest tree only runs in
+    # the manual `release-quality-gate.yml` (after `--profile release`), so a
+    # stale window_scan assertion in this glob stayed red on origin/staging
+    # until listed here.
     "tests/test_rectification_*.py",
     # This file regexes frontend source. Home-split and other page.tsx moves must keep it green.
     "tests/test_supabase_user_data_contract.py",