fix(outages): parse portal address at the boundary; strip district suffix

The outages portal appends the district in parentheses, e.g.
"Медкадры улица, 1 (Заельцовский район)". That suffix hid the house number
from the parser, so every portal address failed house matching and /v1/outages
always returned empty.

- address: NormalizeText drops a trailing "(...)" group (root fix, benefits
  every source)
- outages: introduce HouseUnit; the ArcGIS adapter parses the (cleaned) address
  at the boundary and stores the structured unit; MatchingHouse matches on the
  unit (with a parse fallback for sources that only provide text)
- config: portal.url is now optional (core runs without the events module)
- httpapi: always return "outages": [] (no more omitempty); report
  "detail" when the events module is not configured
- tests: regression coverage for the portal district format

internal/config/config_test.go

@@ -60,10 +60,11 @@ func TestLoadMissingSystemPromptFileFailsClosed(t *testing.T) {
 	}
 }
 
-func TestLoadRequiresPortalURL(t *testing.T) {
+func TestPortalURLOptional(t *testing.T) {
 	dir := t.TempDir()
+	// No portal.url: the events module is disabled, the core still loads.
 	path := writeFile(t, dir, "config.json", `{"addr": ":6171", "data_path": "x.db"}`)
-	if _, err := Load(path); err == nil {
-		t.Fatal("expected error for missing portal.url")
+	if _, err := Load(path); err != nil {
+		t.Fatalf("portal.url must be optional: %v", err)
 	}
 }