feat(tiles): a header names a model read from the CLI's config as such

A session header's tooltip (tile and split) says where a model the CLI did
not report came from; the new `config` source reads
"DeepSeek · qwen3.8-27b (from config)", with the zh-CN pattern
"（来自配置）" (the harness and model names pass through). The header's model
text itself is unchanged. Covered in the chrome tooltip test and the i18n
harvester's exercise.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

test/tile-grid-chrome.test.ts

@@ -182,6 +182,10 @@ describe('the harness logo and the model', () => {
     app._renderTileChrome();
     expect(logoOf('s-b').title).toBe('Claude Code \u00B7 haiku (set at launch)');
     expect(logoOf('s-c').title).toBe('Claude Code \u00B7 qwen3.8-27b (custom endpoint)');
+    app.sessions.get('s-a').displayModel = { model: 'qwen3.8-27b', source: 'config' };
+    app._renderTileChrome();
+    expect(logoOf('s-a').title).toBe('DeepSeek \u00B7 qwen3.8-27b (from config)');
+    expect(modelNameOf('s-a').textContent).toBe('qwen3.8-27b');
     expect(modelNameOf('s-b').textContent).toBe('haiku');
   });