feat: comprehensive test infrastructure improvements

- Fix unit test imports: add env setup in conftest.py before module imports
- Add 24 new auth router tests (RBAC, preferences, password validation)
- Add 16 new tests for litellm and chat_summary routers
- Apply black formatting and ruff linting across codebase
- Add pre-commit hooks configuration (black, ruff, file checks)
- Increase CI coverage threshold from 40% to 50%

Test Results:
- 206 tests passing (91 unit + 115 integration)
- Coverage: 58.79% on core modules
- auth.py: 57% → 85%, litellm.py: 23% → 87%, chat_summary.py: 41% → 100%
- auth_service: 96.51%, config: 100%, rbac: 93.48%

dashboard/backend/routers/terminal.py

@@ -1,13 +1,15 @@
 import asyncio
-import struct
 import logging
 import shlex
-import jwt
+import struct
 from collections import Counter
-from fastapi import WebSocket, Query
+
 import asyncssh
-import config
+import jwt
+from fastapi import Query, WebSocket
+
 import auth_service as auth
+import config
 
 logger = logging.getLogger(__name__)
 
@@ -61,16 +63,18 @@ def build_host_command(host_config: dict) -> str | None:
         f"bash -l -c 'cd /repos/nas-tools && tmux new-session -A -s {quoted_session}'"
     )
 
-    script = " ".join([
-        "if",
-        f"{docker_bin} exec {quoted_container} tmux has-session -t {quoted_session} >/dev/null 2>&1;",
-        "then",
-        f"printf '%sattached\\n' {quoted_marker};",
-        "else",
-        f"printf '%screated\\n' {quoted_marker};",
-        "fi;",
-        f"exec {attach_cmd}",
-    ])
+    script = " ".join(
+        [
+            "if",
+            f"{docker_bin} exec {quoted_container} tmux has-session -t {quoted_session} >/dev/null 2>&1;",
+            "then",
+            f"printf '%sattached\\n' {quoted_marker};",
+            "else",
+            f"printf '%screated\\n' {quoted_marker};",
+            "fi;",
+            f"exec {attach_cmd}",
+        ]
+    )
     return f"bash -lc {shlex.quote(script)}"
 
 
@@ -140,15 +144,17 @@ async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
     try:
         conn = await asyncio.wait_for(
             asyncssh.connect(
-                h["host"], username=h["user"],
-                client_keys=[h["key"]], known_hosts=_known_hosts,
+                h["host"],
+                username=h["user"],
+                client_keys=[h["key"]],
+                known_hosts=_known_hosts,
                 keepalive_interval=15,
                 keepalive_count_max=8,
             ),
-            timeout=10.0
+            timeout=10.0,
         )
         logger.info("SSH connection established to %s", host)
-    except asyncio.TimeoutError:
+    except TimeoutError:
         logger.error("SSH connection to %s timed out after 10s", host)
         await _release_session(session_id)
         await websocket.close(code=1011, reason="SSH connection timeout")
@@ -161,7 +167,9 @@ async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
 
     try:
         process = await conn.create_process(
-            build_host_command(h), term_type="xterm-256color", term_size=(80, 24),
+            build_host_command(h),
+            term_type="xterm-256color",
+            term_size=(80, 24),
             encoding=None,
         )
 
@@ -212,7 +220,7 @@ async def ws_endpoint(websocket: WebSocket, host: str = Query("nas")):
             read_task.cancel()
             try:
                 await asyncio.wait_for(read_task, timeout=2.0)
-            except (asyncio.TimeoutError, asyncio.CancelledError):
+            except (TimeoutError, asyncio.CancelledError):
                 pass
             process.close()
     finally: