fix(review): add Codex last-response test coverage + minor hardening (PR #152)

- Add test/routes/session-routes-codex-last-response.test.ts (app.inject +
  temp CODEX_HOME fixture rollouts): originator match beats cwd fallback when
  two panes share a dir, cwd fallback excludes sibling-claimed/foreign-cwd
  rollouts, resume-uuid filename match, history.jsonl pin outranks originator,
  event_msg/legacy user-turn dedup keeps old-codex turns, injected-context
  filtering, image placeholder, envelope shape ({success:true,data:{text,
  timestamp[,messages]}}), and a Claude-mode regression guard (codex reader
  never consulted for claude sessions)
- Replace clear-at-cap Map caches (codexHistoryPinCache, codexRolloutMetaCache)
  with the repo-standard LRUMap so a full cache wipe can't thrash hot entries
  on large rollout collections
- Join multi-block assistant/user text with a blank line instead of no
  separator (extractCodexBlockText)
- Re-enable the terminal-buffer eye fallback for shell sessions (they have no
  transcript source at all); TUI modes keep the clear placeholder

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

src/web/public/app.js

@@ -1613,11 +1613,12 @@ class CodemanApp {
       let lastResponse = data.text || '';
 
       // Source 2: Terminal buffer fallback — strip ANSI, drop Claude CLI chrome.
-      // Claude-only: _cleanTerminalBuffer knows Claude CLI's output; for TUI
-      // modes (codex/opencode/gemini) it yields repaint garbage, so a clear
+      // Claude + shell only: _cleanTerminalBuffer knows Claude CLI's output, and
+      // shell sessions have no transcript source at all; for TUI modes
+      // (codex/opencode/gemini) it yields repaint garbage, so a clear
       // placeholder beats a messy screen dump there.
       const sessionMode = this.sessions.get(this.activeSessionId)?.mode || 'claude';
-      if (!lastResponse && sessionMode === 'claude') {
+      if (!lastResponse && (sessionMode === 'claude' || sessionMode === 'shell')) {
         const termRes = await fetch(`/api/sessions/${this.activeSessionId}/terminal`);
         const termData = (await termRes.json())?.data ?? {};
         if (termData.terminalBuffer) {