chore(backend): repair test suite and bring ruff to green

The suite hadn't run green since the routes refactor:
- test_profile_duplicate_names.py imported the pre-refactor module
  layout and broke collection; now imports backend.services.profiles
- tests/conftest.py puts the repo root and backend dir on sys.path so
  files collect standalone instead of depending on run order
- test_cors.py tested a hand-copied mirror of the origin list that had
  drifted from app.py (missing http://tauri.localhost); it now builds
  the app via the real create_app() factory
- test_progress.py simulated a 1KB download, below the tracker's 1MB
  reporting threshold; simulation raised to 5MB
- slow/timeout markers registered in pyproject

Ruff: ~900 violations auto-fixed (typing modernization, import
sorting, unused imports, whitespace). The remaining rules are baselined
in pyproject.toml with per-rule counts to burn down, plus per-file
carve-outs for deliberate env-before-import ordering. ruff check is
now clean; suite is 134 passed, 2 skipped.

backend/tests/test_progress.py

@@ -4,9 +4,8 @@ Test script to debug model download progress tracking.
 
 import asyncio
 import json
-import time
-from typing import List, Dict
 import logging
+import time
 
 # Set up logging to see what's happening
 logging.basicConfig(
@@ -14,8 +13,8 @@ logging.basicConfig(
     format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
 )
 
-from utils.progress import ProgressManager, get_progress_manager
 from utils.hf_progress import HFProgressTracker, create_hf_progress_callback
+from utils.progress import ProgressManager, get_progress_manager
 
 
 def test_progress_manager_basic():
@@ -61,7 +60,7 @@ async def test_progress_manager_sse():
     print("=" * 60)
 
     pm = ProgressManager()
-    collected_events: List[Dict] = []
+    collected_events: list[dict] = []
 
     # Simulate SSE client
     async def sse_client():
@@ -123,7 +122,7 @@ def test_hf_progress_tracker():
     print("Test 3: HFProgressTracker tqdm Patching")
     print("=" * 60)
 
-    captured_progress: List[tuple] = []
+    captured_progress: list[tuple] = []
 
     def progress_callback(downloaded: int, total: int, filename: str):
         """Capture progress updates."""
@@ -137,12 +136,14 @@ def test_hf_progress_tracker():
         try:
             from tqdm import tqdm
 
-            # Simulate downloading a file
+            # Simulate downloading a file. The tracker only reports once the
+            # combined total crosses MIN_TOTAL_BYTES (1 MB), so the simulated
+            # file must be larger than that.
             print("  Simulating download with tqdm...")
-            total_size = 1000
+            total_size = 5_000_000
             with tqdm(total=total_size, desc="model.bin", unit="B", unit_scale=True) as pbar:
-                for chunk in range(0, total_size, 100):
-                    pbar.update(100)
+                for chunk in range(0, total_size, 500_000):
+                    pbar.update(500_000)
                     time.sleep(0.01)
 
             print(f"  Captured {len(captured_progress)} progress updates")
@@ -170,7 +171,7 @@ async def test_full_integration():
     print("=" * 60)
 
     pm = get_progress_manager()
-    collected_events: List[Dict] = []
+    collected_events: list[dict] = []
 
     # SSE client
     async def sse_client():
@@ -244,9 +245,8 @@ async def test_full_integration():
         assert collected_events[-1]["status"] == "complete", "Should end with 'complete'"
         print("✓ Test 4 PASSED\n")
         return True
-    else:
-        print("✗ Test 4 FAILED - No events received\n")
-        return False
+    print("✗ Test 4 FAILED - No events received\n")
+    return False
 
 
 async def main():