docs: add .agents workspace and the Astro refactor plan

Adds the agent-facing workspace and a 20-task plan for migrating the site
to Astro. Nothing here implements the refactor; these are briefs, rules and
templates that the task agents read.

- .agents/ holds context, rules, checklists, skills, specialist agents,
  component/page/config templates and gate scripts. It is vendor-neutral so
  MiniMax, Gemini and Codex can all read it; CLAUDE.md just points at
  AGENTS.md.
- .husky/ plus .lintstagedrc.json wire the three gate tiers. gate.sh locks on
  the shared git-common-dir so parallel worktrees serialise, and guards the
  assertion count in scripts/verify.mjs against a coverage drop.
- plans/astro-refactor/ carries the phase graph, per-task briefs and the
  model-routing recommendation.

These files must be tracked before fanning out: a worktree only checks out
tracked files, so an untracked plan is invisible to every agent working in one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.agents/ORCHESTRATOR.md

@@ -0,0 +1,64 @@
+# Orchestrator
+
+Map of `.agents/`, and how to pick who does what.
+
+## Layout
+
+```
+.agents/
+  ORCHESTRATOR.md      you are here
+  context/             how things are — read before deciding
+  rules/               how things must be — binding
+  checklists/          gates to run before you claim done
+  skills/              procedures an agent loads on demand
+  agents/              specialist agent definitions
+  templates/           component and page starting points
+  scripts/             deterministic helpers (prefer these over prose)
+```
+
+`context/` describes reality, `rules/` constrain change. When they disagree,
+reality won — update the rule and say so.
+
+## Specialists
+
+Each agent has one responsibility, one set of rules, and its own worktree.
+Full definitions in [`agents/`](agents/).
+
+| Agent | Owns | Loads skills |
+| --- | --- | --- |
+| [`astro-architect`](agents/astro-architect.md) | project scaffold, config, routing, layouts | `astro-page` |
+| [`design-system-keeper`](agents/design-system-keeper.md) | tokens, the single palette, type scale | `design-tokens` |
+| [`component-builder`](agents/component-builder.md) | one component per task, from templates | `astro-component`, `design-tokens` |
+| [`page-migrator`](agents/page-migrator.md) | one page per task, HTML → `.astro` | `astro-page`, `content-migration` |
+| [`motion-designer`](agents/motion-designer.md) | transitions, islands with animation | `motion` |
+| [`content-i18n-migrator`](agents/content-i18n-migrator.md) | strings out of `app.js` into content collections | `content-migration` |
+| [`verification-engineer`](agents/verification-engineer.md) | keeping `verify.mjs` meaningful across the refactor | `verify-contract`, `visual-regression` |
+| [`reviewer`](agents/reviewer.md) | merge gate; reads diffs, never writes features | all |
+
+## Working agreement
+
+1. **One task, one worktree, one agent.** See [`rules/git-worktrees.md`](rules/git-worktrees.md).
+2. **Read `context/` first.** Especially `design-system.md` and `verification.md`.
+   Most wrong answers here come from assuming the CSS is already coherent.
+3. **Templates over invention.** `templates/components/` and `templates/pages/`
+   exist so ten parallel agents produce one house style, not ten.
+4. **The gate is `npm run verify` plus the relevant checklist.** Green tests
+   with deleted assertions is a failed task.
+5. **Report what you did not do.** Partial work with an honest boundary is
+   useful; silent narrowing is not.
+
+## Task flow
+
+```
+plans/astro-refactor/task-NN.md   ← the brief
+        ↓
+git worktree add ../af-task-NN    ← isolation
+        ↓
+agent loads .agents/agents/<role>.md + its skills
+        ↓
+checklists/before-*.md            ← self-gate
+        ↓
+npm run verify                    ← hard gate
+        ↓
+reviewer agent on the diff        ← merge gate
+```