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.go

@@ -32,7 +32,8 @@ type ResolveConfig struct {
 	MaxCandidates   int     `json:"max_candidates"`
 }
 
-// PortalConfig configures the external outages portal (ArcGIS).
+// PortalConfig configures the external outages portal (ArcGIS). When URL is
+// empty the "events by house" module is disabled and only /v1/resolve works.
 type PortalConfig struct {
 	URL            string `json:"url"`
 	TimeoutSeconds int    `json:"timeout_seconds"`
@@ -116,9 +117,8 @@ func (c Config) validate() error {
 	if c.LLM.Enabled && c.LLM.URL == "" {
 		return fmt.Errorf("config: llm.url is required when llm.enabled is true")
 	}
-	if c.Portal.URL == "" {
-		return fmt.Errorf("config: portal.url is required")
-	}
+	// portal.url is optional: without it the "events by house" module is
+	// disabled and only /v1/resolve is served.
 	return nil
 }