docs: add OpenAPI responses={} to all router endpoints

Add explicit HTTP status code documentation to every endpoint
across 15 router files. Each endpoint now declares all possible
response codes (200/201/204/400/401/404/409/429/502/503) with
descriptions so frontend can distinguish error types.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/app/routers/config_misc.py

@@ -111,6 +111,11 @@ def _validate_log_target(value: str) -> None:
     "/global",
     response_model=GlobalConfigResponse,
     summary="Return global fail2ban settings",
+    responses={
+        200: {"description": "Global config returned", "model": GlobalConfigResponse},
+        401: {"description": "Session missing, expired, or invalid"},
+        502: {"description": "fail2ban unreachable"},
+    },
 )
 async def get_global_config(
     _request: Request,
@@ -140,6 +145,13 @@ async def get_global_config(
     status_code=status.HTTP_204_NO_CONTENT,
     summary="Update global fail2ban settings",
     dependencies=[Depends(_check_config_update_rate_limit)],
+    responses={
+        204: {"description": "Global config updated successfully"},
+        400: {"description": "Set command rejected or log_target invalid"},
+        401: {"description": "Session missing, expired, or invalid"},
+        429: {"description": "Rate limit exceeded for config update operations"},
+        502: {"description": "fail2ban unreachable"},
+    },
 )
 async def update_global_config(
     _request: Request,
@@ -171,6 +183,12 @@ async def update_global_config(
     "/reload",
     status_code=status.HTTP_204_NO_CONTENT,
     summary="Reload fail2ban to apply configuration changes",
+    responses={
+        204: {"description": "Fail2ban reloaded successfully"},
+        401: {"description": "Session missing, expired, or invalid"},
+        409: {"description": "Reload command failed in fail2ban"},
+        502: {"description": "fail2ban unreachable"},
+    },
 )
 async def reload_fail2ban(
     _request: Request,
@@ -199,6 +217,13 @@ async def reload_fail2ban(
     "/restart",
     status_code=status.HTTP_204_NO_CONTENT,
     summary="Restart the fail2ban service",
+    responses={
+        204: {"description": "Fail2ban restarted successfully"},
+        401: {"description": "Session missing, expired, or invalid"},
+        409: {"description": "Stop command failed in fail2ban"},
+        502: {"description": "fail2ban unreachable for stop command"},
+        503: {"description": "fail2ban did not come back online within 10s"},
+    },
 )
 async def restart_fail2ban(
     _request: Request,
@@ -252,6 +277,11 @@ async def restart_fail2ban(
     "/regex-test",
     response_model=RegexTestResponse,
     summary="Test a fail regex pattern against a sample log line",
+    responses={
+        200: {"description": "Regex test result", "model": RegexTestResponse},
+        401: {"description": "Session missing, expired, or invalid"},
+        422: {"description": "Invalid regex pattern"},
+    },
 )
 async def regex_test(
     _auth: AuthDep,
@@ -281,6 +311,11 @@ async def regex_test(
     "/preview-log",
     response_model=LogPreviewResponse,
     summary="Preview log file lines against a regex pattern",
+    responses={
+        200: {"description": "Log preview result", "model": LogPreviewResponse},
+        401: {"description": "Session missing, expired, or invalid"},
+        422: {"description": "Invalid regex pattern"},
+    },
 )
 async def preview_log(
     _auth: AuthDep,
@@ -310,6 +345,10 @@ async def preview_log(
     "/map-color-thresholds",
     response_model=MapColorThresholdsResponse,
     summary="Get map color threshold configuration",
+    responses={
+        200: {"description": "Color thresholds returned", "model": MapColorThresholdsResponse},
+        401: {"description": "Session missing, expired, or invalid"},
+    },
 )
 async def get_map_color_thresholds(
     _request: Request,
@@ -334,6 +373,12 @@ async def get_map_color_thresholds(
     response_model=MapColorThresholdsResponse,
     summary="Update map color threshold configuration",
     dependencies=[Depends(_check_config_update_rate_limit)],
+    responses={
+        200: {"description": "Color thresholds updated", "model": MapColorThresholdsResponse},
+        400: {"description": "Validation error (thresholds not properly ordered)"},
+        401: {"description": "Session missing, expired, or invalid"},
+        429: {"description": "Rate limit exceeded for config update operations"},
+    },
 )
 async def update_map_color_thresholds(
     _request: Request,
@@ -365,6 +410,12 @@ async def update_map_color_thresholds(
     "/fail2ban-log",
     response_model=Fail2BanLogResponse,
     summary="Read the tail of the fail2ban daemon log file",
+    responses={
+        200: {"description": "Log file lines returned", "model": Fail2BanLogResponse},
+        400: {"description": "Log target not a file or path outside allowed directory"},
+        401: {"description": "Session missing, expired, or invalid"},
+        502: {"description": "fail2ban unreachable"},
+    },
 )
 async def get_fail2ban_log(
     _request: Request,
@@ -416,6 +467,11 @@ async def get_fail2ban_log(
     "/service-status",
     response_model=ServiceStatusResponse,
     summary="Return fail2ban service health status with log configuration",
+    responses={
+        200: {"description": "Service status returned", "model": ServiceStatusResponse},
+        401: {"description": "Session missing, expired, or invalid"},
+        502: {"description": "fail2ban unreachable"},
+    },
 )
 async def get_service_status(
     _request: Request,