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

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,29 @@
+name: Feature Request
+description: Suggest a new feature or improvement
+labels: ["enhancement"]
+title: "[Feature] "
+body:
+
+- type: markdown
+  attributes:
+    value: |
+      ## Feature Description
+      Describe the feature you'd like and why it would be useful.
+
+- type: textarea
+  id: usecase
+  attributes:
+    label: Use Case
+    placeholder: Who would use this and what problem does it solve?
+
+- type: textarea
+  id: alternatives
+  attributes:
+    label: Alternatives Considered
+    placeholder: What other approaches did you consider?
+
+- type: textarea
+  id: context
+  attributes:
+    label: Additional Context
+    placeholder: Screenshots, mockups, or any other relevant information.