fix(codex): preserve reasoning entries as thinking blocks

Codex history normalization was downgrading reasoning into plain assistant text
because of branch ordering, not because the raw data was missing.

Why this mattered:
- Codex reasoning JSONL entries are intentionally mapped to history items with
  type thinking, but they also carry message.role assistant.
- normalizeHistoryEntry evaluated the assistant-role branch before the
  thinking branch.
- As a result, reasoning content matched the assistant-text path first and was
  emitted as kind text instead of kind thinking.
- This collapses semantic intent, so UI and downstream features that rely on
  thinking blocks (separate rendering, filtering, and interpretation of model
  thought process vs final answer) receive the wrong message kind.

What changed:
- Prioritized thinking detection (raw.type === thinking or raw.isReasoning)
  before role-based assistant normalization.
- Kept a non-empty content guard for thinking payloads to avoid emitting empty
  artifacts.

Impact:
- Reasoning entries from persisted Codex JSONL now remain thinking blocks
  end-to-end.
- Regular assistant text normalization behavior remains unchanged.

server/modules/providers/list/codex/codex-sessions.provider.ts

@@ -270,6 +270,23 @@ export class CodexSessionsProvider implements IProviderSessions {
     const ts = raw.timestamp || new Date().toISOString();
     const baseId = raw.uuid || generateMessageId('codex');
 
+    if (raw.type === 'thinking' || raw.isReasoning) {
+      const thinkingContent = typeof raw.message?.content === 'string'
+        ? raw.message.content
+        : '';
+      if (!thinkingContent.trim()) {
+        return [];
+      }
+      return [createNormalizedMessage({
+        id: baseId,
+        sessionId,
+        timestamp: ts,
+        provider: PROVIDER,
+        kind: 'thinking',
+        content: thinkingContent,
+      })];
+    }
+
     if (raw.message?.role === 'user') {
       const content = typeof raw.message.content === 'string'
         ? raw.message.content
@@ -316,17 +333,6 @@ export class CodexSessionsProvider implements IProviderSessions {
       })];
     }
 
-    if (raw.type === 'thinking' || raw.isReasoning) {
-      return [createNormalizedMessage({
-        id: baseId,
-        sessionId,
-        timestamp: ts,
-        provider: PROVIDER,
-        kind: 'thinking',
-        content: raw.message?.content || '',
-      })];
-    }
-
     if (raw.type === 'tool_use' || raw.toolName) {
       return [createNormalizedMessage({
         id: baseId,