Add origin field and filter for ban sources (Tasks 1 & 2)

- Task 1: Mark imported blocklist IP addresses
  - Add BanOrigin type and _derive_origin() to ban.py model
  - Populate origin field in ban_service list_bans() and bans_by_country()
  - BanTable and MapPage companion table show origin badge column
  - Tests: origin derivation in test_ban_service.py and test_dashboard.py

- Task 2: Add origin filter to dashboard and world map
  - ban_service: _origin_sql_filter() helper; origin param on list_bans()
    and bans_by_country()
  - dashboard router: optional origin query param forwarded to service
  - Frontend: BanOriginFilter type + BAN_ORIGIN_FILTER_LABELS in ban.ts
  - fetchBans / fetchBansByCountry forward origin to API
  - useBans / useMapData accept and pass origin; page resets on change
  - BanTable accepts origin prop; DashboardPage adds segmented filter
  - MapPage adds origin Select next to time-range picker
  - Tests: origin filter assertions in test_ban_service and test_dashboard

backend/app/models/config.py

@@ -169,3 +169,36 @@ class LogPreviewResponse(BaseModel):
     total_lines: int = Field(..., ge=0)
     matched_count: int = Field(..., ge=0)
     regex_error: str | None = Field(default=None, description="Set if the regex failed to compile.")
+
+
+# ---------------------------------------------------------------------------
+# Map color threshold models
+# ---------------------------------------------------------------------------
+
+
+class MapColorThresholdsResponse(BaseModel):
+    """Response for ``GET /api/config/map-thresholds``."""
+
+    model_config = ConfigDict(strict=True)
+
+    threshold_high: int = Field(
+        ..., description="Ban count for red coloring."
+    )
+    threshold_medium: int = Field(
+        ..., description="Ban count for yellow coloring."
+    )
+    threshold_low: int = Field(
+        ..., description="Ban count for green coloring."
+    )
+
+
+class MapColorThresholdsUpdate(BaseModel):
+    """Payload for ``PUT /api/config/map-thresholds``."""
+
+    model_config = ConfigDict(strict=True)
+
+    threshold_high: int = Field(..., gt=0, description="Ban count for red.")
+    threshold_medium: int = Field(
+        ..., gt=0, description="Ban count for yellow."
+    )
+    threshold_low: int = Field(..., gt=0, description="Ban count for green.")