fix(ai_client): add patch_callback param to _send_gemini_cli signature

conductor/tracks/tier4_auto_patching_20260306/plan.md

@@ -37,7 +37,7 @@ Focus: Generate unified diff on test failure
 ## Phase 2: Diff Viewer UI
 Focus: Display side-by-side diff
 
-- [ ] Task 2.1: Parse unified diff
+- [x] Task 2.1: Parse unified diff
     - WHERE: `src/gui_2.py` or new `src/diff_viewer.py`
     - WHAT: Parse diff into hunks
     - HOW:
@@ -55,7 +55,7 @@ Focus: Display side-by-side diff
        return hunks
       ```
 
-- [ ] Task 2.2: Render diff viewer
+- [x] Task 2.2: Render diff viewer
     - WHERE: `src/gui_2.py`
     - WHAT: Color-coded diff display
     - HOW:
@@ -73,7 +73,7 @@ Focus: Display side-by-side diff
 ## Phase 3: Patch Application
 Focus: Apply patch with backup
 
-- [ ] Task 3.1: Create backup before apply
+- [x] Task 3.1: Create backup before apply
     - WHERE: `src/gui_2.py` or `src/mcp_client.py`
     - WHAT: Backup file to .backup
     - HOW:
@@ -83,7 +83,7 @@ Focus: Apply patch with backup
       shutil.copy(file_path, backup_path)
       ```
 
-- [ ] Task 3.2: Apply patch
+- [x] Task 3.2: Apply patch
     - WHERE: `src/gui_2.py`
     - WHAT: Use patch command or difflib
     - HOW:
@@ -92,7 +92,7 @@ Focus: Apply patch with backup
       result = subprocess.run(["patch", "-p1"], input=diff_text, capture_output=True, text=True)
       ```
 
-- [ ] Task 3.3: Restore on failure
+- [x] Task 3.3: Restore on failure
     - WHERE: `src/gui_2.py`
     - WHAT: Restore from backup if patch fails
     - HOW: `shutil.copy(backup_path, file_path)`
@@ -100,7 +100,7 @@ Focus: Apply patch with backup
 ## Phase 4: Modal UI
 Focus: Approval modal for patches
 
-- [ ] Task 4.1: Create patch approval modal
+- [x] Task 4.1: Create patch approval modal
     - WHERE: `src/gui_2.py`
     - WHAT: Modal with diff preview and Apply/Reject buttons
     - HOW: