feat: agent loop harness with Claude Code plugin support

Generator-evaluator architecture with iterative context-reset for
long-running coding tasks. Ships as a Claude Code plugin — install
with /plugin and use /agent-loop:init, /agent-loop:plan, /agent-loop:run.

lib/hooks.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+# Stop hook management for Claude Code loop continuation.
+#
+# NOTE: Hooks are currently no-ops. The loop uses `claude --print` (non-interactive),
+# which runs to completion and exits naturally — no Stop hook is needed to signal
+# iteration boundaries. The install/remove interface is preserved so that a future
+# interactive mode can be added without changing loop.sh's call sites.
+#
+# If interactive mode is added, the hook mechanism will need redesign: `kill -INT $PPID`
+# targets the hook runner's parent (Claude Code), not loop.sh. A sentinel-file or
+# named-pipe approach would be more reliable.
+
+install_hooks() {
+    :  # no-op — see note above
+}
+
+remove_hooks() {
+    :  # no-op — see note above
+}