feat: add codex-worktree session adapter

Adds the third session adapter (after dmux-tmux and claude-history),
normalizing Codex rollout sessions into the harness-neutral
ecc.session.v1 snapshot. Reads ~/.codex/sessions rollout JSONL,
derives objective (skipping the AGENTS.md preamble + leading message
UUID), model, originator, worktree cwd, and best-effort git branch.

This is step 1 of ECC-2.0-SESSION-ADAPTER-DISCOVERY (move the
abstraction beyond tmux + Claude-history) and supports the
wrap/adapt control-pane strategy: ECC reads sessions from any
harness rather than owning one UX.

- scripts/lib/session-adapters/codex-worktree.js: adapter + rollout parser
- canonical-session.js: normalizeCodexWorktreeSession
- registry.js: register adapter, codex/codex-worktree target types
- tests/lib/session-adapters-codex.test.js: 4 tests (unit + registry routing)

scripts/lib/session-adapters/registry.js

@@ -2,13 +2,16 @@
 
 const { createClaudeHistoryAdapter } = require('./claude-history');
 const { createDmuxTmuxAdapter } = require('./dmux-tmux');
+const { createCodexWorktreeAdapter } = require('./codex-worktree');
 
 const TARGET_TYPE_TO_ADAPTER_ID = Object.freeze({
   plan: 'dmux-tmux',
   session: 'dmux-tmux',
   'claude-history': 'claude-history',
   'claude-alias': 'claude-history',
-  'session-file': 'claude-history'
+  'session-file': 'claude-history',
+  'codex-worktree': 'codex-worktree',
+  codex: 'codex-worktree'
 });
 
 function buildDefaultAdapterOptions(options, adapterId) {
@@ -30,7 +33,8 @@ function buildDefaultAdapterOptions(options, adapterId) {
 function createDefaultAdapters(options = {}) {
   return [
     createClaudeHistoryAdapter(buildDefaultAdapterOptions(options, 'claude-history')),
-    createDmuxTmuxAdapter(buildDefaultAdapterOptions(options, 'dmux-tmux'))
+    createDmuxTmuxAdapter(buildDefaultAdapterOptions(options, 'dmux-tmux')),
+    createCodexWorktreeAdapter(buildDefaultAdapterOptions(options, 'codex-worktree'))
   ];
 }
 
@@ -69,6 +73,13 @@ function normalizeStructuredTarget(target, context = {}) {
     };
   }
 
+  if (type === 'codex-worktree' || type === 'codex') {
+    return {
+      target: `codex:${value}`,
+      context: nextContext
+    };
+  }
+
   return {
     target: value,
     context: nextContext