Keep Codex hooks manifest in plugin metadata

Prompt: Jesse questioned whether the PR should remove the hooks config from the Codex plugin manifest.

Runtime investigation showed Codex accepts a committed plugin manifest with hooks and installs the plugin successfully. Removing the field changes behavior: Codex falls back to the default hooks/hooks.json, which uses the non-Codex session-start hook and CLAUDE_PLUGIN_ROOT path, instead of hooks/hooks-codex.json and the session-start-codex script.

Changes: restore .codex-plugin/plugin.json hooks to ./hooks/hooks-codex.json and update the Codex marketplace manifest test to require that Codex-specific hook pointer instead of rejecting hooks.

Validation: bash tests/codex/test-marketplace-manifest.sh; scripts/lint-shell.sh tests/codex/test-marketplace-manifest.sh; bash tests/codex-plugin-sync/test-sync-to-codex-plugin.sh; bash tests/kimi/test-plugin-manifest.sh; bash tests/shell-lint/test-lint-shell.sh.

.codex-plugin/plugin.json

@@ -21,6 +21,7 @@
     "workflow"
   ],
   "skills": "./skills/",
+  "hooks": "./hooks/hooks-codex.json",
   "interface": {
     "displayName": "Superpowers",
     "shortDescription": "Planning, TDD, debugging, and delivery workflows for coding agents",

hooks/hooks-codex.json

@@ -0,0 +1,16 @@
+{
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "startup|resume|clear",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "\"${PLUGIN_ROOT}/hooks/run-hook.cmd\" session-start-codex",
+            "async": false
+          }
+        ]
+      }
+    ]
+  }
+}