Add branch-cleanup task, fix taplo-lint pre-commit hook

- mise-tasks/branch-cleanup: delete merged local/remote branches via
  git + Forgejo API (1Password/env/flag token resolution)
- mise.toml: add uv (runs PEP 723 task scripts) and bat (ai-docs output)
- CLAUDE.md: re-point at AGENTS.md
- prek.toml: drop taplo-lint hook. It fetches the remote SchemaStore
  catalog, which the pinned (dormant) taplo CLI can no longer decode and
  which fails in sandboxed CI. check-toml still validates syntax and
  taplo-format still formats.
- .forgejo workflows / .gitea/template / dagger: minor resync

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.dagger/src/project_template_ci/main.py

@@ -10,7 +10,7 @@ class ProjectTemplateCi:
         """Build Quartz docs site. Returns docs tarball."""
         return await (
             dag.container()
-            .from_("node:22-slim")
+            .from_("node:24-slim")
             .with_exec(["apt-get", "update", "-qq"])
             .with_exec(["apt-get", "install", "-y", "-qq", "git"])
             .with_directory("/workspace", src)