chore: adopt trunk-based development

Closes #27.

PROJECT.md
- Git section: TBD as the convention. Commit to main, one logical
  change per commit, `task check` locally before push, CI is the
  quality gate. PRs only for the parallel-agent exception.
- Agent rule 6: rewritten to match.

.gitea/workflows/cd.yml
- Drop the pull_request trigger — vestigial under TBD.
- Drop the `if: github.event_name != 'pull_request'` guard on the
  build job (now always true since pull_request no longer fires).
  Tag pushes still build (no version gating regression).
- Deploy `if` left alone — already correctly limits deploy to
  main pushes, skipping tag-push builds.

.githooks/pre-push (new)
- Runs `task check` before every push. Set up via `task setup:hooks`,
  which sets core.hooksPath to the in-repo .githooks dir.

Taskfile.yml
- New `setup:hooks` task to install the pre-push hook on a fresh
  clone.

README.md
- Quickstart section showing `task setup:hooks` + the TBD policy.

Derived adapters regenerated via `task context:sync` and committed
in the same commit (single-commit invariant).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.context/PROJECT.md

@@ -37,9 +37,11 @@
 
 ### Git
 - Conventional commits: `feat:`, `fix:`, `chore:`, `docs:`, `refactor:`
-- Branch naming: `feat/short-description`, `fix/short-description`
-- PRs: one concern per PR, description explains *why* not *what*
-- **Branch protection:** always work on a feature branch, open a PR, never push directly to main
+- **Trunk-Based Development:** commit directly to main. One logical change per commit.
+- Run `task check` locally before every push. CI is the quality gate, not branch protection.
+- No feature branches, no PRs for solo/agent work.
+- Exception: if a parallel agent session is active on this repo, use a short-lived
+  `agent/<description>` branch and merge within the same session.
 
 ### Security
 - No secrets in code, ever — use env vars or SOPS-encrypted files
@@ -77,7 +79,8 @@ When acting as a coding agent on this project:
 3. If unsure about a convention, check `DECISIONS.md` or ask
 4. Never modify files outside the project root without explicit permission
 5. When adding a dependency, explain why in the commit message
-6. Always work on a feature branch and open a PR — never push directly to main
+6. Commit directly to main. Run `task check` before every push. Never create
+   feature branches unless a parallel agent is simultaneously active on this repo.
 7. For client projects: never send code or context to cloud APIs — use local models via LiteLLM
 
 ## Current state — v0.2.5 (2026-05-17)