fix: improve terminal buffer cleaning and test reliability

- Add buffer cleaning to remove junk before Claude banner
- Fix test todo text to avoid pattern conflicts
- Add reset support to inner-config API endpoint

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test/respawn-controller.test.ts

@@ -21,6 +21,11 @@ class MockSession extends EventEmitter {
     this.writeBuffer.push(data);
   }
 
+  writeViaScreen(data: string): boolean {
+    this.writeBuffer.push(data);
+    return true;
+  }
+
   // Simulate terminal output
   simulateTerminalOutput(data: string): void {
     this.emit('terminal', data);