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

frontend/src/App.tsx

@@ -15,6 +15,7 @@ const Activity = lazy(() => import('./pages/Activity'))
 const Blocklist = lazy(() => import('./pages/Blocklist'))
 const Settings = lazy(() => import('./pages/Settings'))
 const Search = lazy(() => import('./pages/Search'))
+const SemanticSearch = lazy(() => import('./pages/SemanticSearch'))
 
 const navItems = [
   { to: '/', label: 'Dashboard' },
@@ -23,6 +24,7 @@ const navItems = [
   { to: '/calendar', label: 'Calendar' },
   { to: '/queue', label: 'Queue' },
   { to: '/search', label: 'Search' },
+  { to: '/semantic-search', label: 'Semantic Search' },
   { to: '/activity', label: 'Activity' },
   { to: '/requests', label: 'Requests' },
   { to: '/blocklist', label: 'Blocklist' },
@@ -62,6 +64,7 @@ export default function App() {
                 <Route path="/library/:type/:id" element={<MediaDetail />} />
                 <Route path="/queue" element={<Queue />} />
                 <Route path="/search" element={<Search />} />
+                <Route path="/semantic-search" element={<SemanticSearch />} />
                 <Route path="/activity" element={<Activity />} />
                 <Route path="/requests" element={<Requests />} />
                 <Route path="/blocklist" element={<Blocklist />} />