fix(session-runtime): make Gemini auth handling and Codex resume state deterministic

Why:
- Gemini exit-code 41 auth guidance was defined in two places with slightly different wording, which creates drift and inconsistent UX when auth fails.
- Gemini env bootstrap only short-circuited when *all* auth-related vars were present; that forced unnecessary user-level env file reads even when a valid primary credential already existed.
- Codex session registration only populated the active-session map when an id was unseen; resumed sessions could retain stale thread/abort/status objects, leading to incorrect lifecycle behavior.
- Debug console logs in runtime request paths added noise without operational value.

What changed:
- Removed exit-code 41 from mapGeminiExitCodeToMessage and kept a single authoritative 41 message in the close-handler auth branch.
- Aligned 41 remediation phrasing to consistently reference a valid GEMINI_API_KEY.
- Updated uildGeminiProcessEnv to return early when any primary auth signal is already present (GEMINI_API_KEY, GOOGLE_API_KEY, or GOOGLE_APPLICATION_CREDENTIALS).
- Changed Codex 
egisterSession to always overwrite session state for valid ids so resumed runs replace stale entries.
- Removed unnecessary console.log debug statements in touched runtime paths, including the chat submit debug log.

Impact:
- More predictable Gemini authentication error messaging.
- Avoids needless env-file fallback when credentials are already available.
- Prevents stale Codex session controllers/status from leaking across resumes.
- Cleaner logs with no behavior change to error/warn reporting.

server/openai-codex.js

@@ -232,21 +232,17 @@ export async function queryCodex(command, options = {}, ws) {
       thread = codex.startThread(threadOptions);
     }
 
-    console.log(`[Codex] Started thread, sandboxMode: ${sandboxMode}, approvalPolicy: ${approvalPolicy}`);
-
     const registerSession = (id) => {
       if (!id) {
         return;
       }
-      if (!activeCodexSessions.has(id)) {
-        activeCodexSessions.set(id, {
-          thread,
-          codex,
-          status: 'running',
-          abortController,
-          startedAt: new Date().toISOString()
-        });
-      }
+      activeCodexSessions.set(id, {
+        thread,
+        codex,
+        status: 'running',
+        abortController,
+        startedAt: new Date().toISOString()
+      });
     };
 
     // Existing sessions can be tracked immediately; new sessions are tracked after thread.started.