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/scripts/verify-hooks.sh

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+# Guards the silent-failure mode described in .agents/rules/gates.md.
+#
+# Husky points core.hooksPath at `.husky/_`, but that directory is GENERATED by
+# `npm install` and is NOT committed. A fresh `git worktree add` therefore has
+# hooks configured and the directory missing — so every hook silently does
+# nothing and every commit passes unchecked.
+#
+# Run this in any worktree you did not create with worktree.sh.
+set -euo pipefail
+
+cd "$(git rev-parse --show-toplevel)"
+fail=0
+
+path=$(git config --get core.hooksPath || true)
+if [ -z "$path" ]; then
+  echo "✗ core.hooksPath is unset — husky was never installed here"
+  fail=1
+else
+  echo "✓ core.hooksPath = $path"
+fi
+
+if [ ! -d "${path:-.husky/_}" ]; then
+  echo "✗ ${path:-.husky/_}/ does not exist — HOOKS ARE NOT RUNNING"
+  fail=1
+else
+  echo "✓ ${path} exists"
+fi
+
+for hook in pre-commit commit-msg pre-push; do
+  if [ -f ".husky/$hook" ]; then
+    echo "✓ .husky/$hook present"
+  else
+    echo "✗ .husky/$hook missing"
+    fail=1
+  fi
+done
+
+if [ ! -d node_modules ]; then
+  echo "✗ node_modules missing — lint-staged and astro check cannot run"
+  fail=1
+fi
+
+if [ "$fail" -ne 0 ]; then
+  echo
+  echo "Fix: npm ci --prefer-offline   (its prepare script regenerates .husky/_)"
+  exit 1
+fi
+
+echo
+echo "hooks are live in this worktree"