feat: semantic search with Qdrant + Ollama embeddings

- Add SemanticSearchService with embed() + searchQdrant() methods
- Add GET /api/search/semantic endpoint (?q=query&k=5)
- Wire SemanticSearchService into router and cmd/server/main.go
- Add SemanticSearch React page with results + similarity scores
- Add 'Semantic Search' nav link in App.tsx
- Add unit tests with mocked Ollama + Qdrant HTTP servers (4 tests, all passing)
- Add GitHub issue templates (bug report, feature request)
- Add pull request template

internal/api/router.go

@@ -35,6 +35,7 @@ type Services struct {
 	Discover       *service.DiscoverService
 	MediaDetail    *service.MediaDetailService
 	Calendar       *service.CalendarService
+	SemanticSearch *service.SemanticSearchService
 }
 
 func NewRouter(cfg *config.Config, svc *Services) *echo.Echo {
@@ -148,6 +149,11 @@ func NewRouter(cfg *config.Config, svc *Services) *echo.Echo {
 	// Calendar route
 	g.GET("/calendar", listCalendarEvents(svc.Calendar))
 
+	// Semantic search route
+	if svc.SemanticSearch != nil {
+		g.GET("/search/semantic", semanticSearch(svc.SemanticSearch))
+	}
+
 	// Request routes — protected by API key auth
 	apiKeyAuth := newAPIKeyAuth(svc.User)
 	g.GET("/requests", listRequests(svc.Request, svc.User), apiKeyAuth)