refactor: rename project Lyria Studio → Kithara Studio

- App name, UI text, page titles → Kithara Studio
- Python module: lyria_client.py → kithara_client.py
- Tailwind color classes: lyria-* → kithara-*
- CSS custom properties: --lyria-* → --kithara-*
- Database: lyria.db → kithara.db
- Package name: kithara-studio-frontend
- localStorage key: kithara-saved-searches
- Add project logo (lyre icon, black on transparent, invert via CSS)

Preserved as Google's property:
- LYRIA_API_KEY, LYRIA_BASE_URL, LYRIA_DEFAULT_MODEL env vars
- LYRIA_MODELS dict and model IDs (lyria-3-clip-preview, lyria-3-pro-preview)
- Google Lyria API references in error messages and docstrings

frontend/package-lock.json

@@ -1,11 +1,11 @@
 {
-  "name": "lyria-studio-frontend",
+  "name": "kithara-studio-frontend",
   "version": "0.1.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "lyria-studio-frontend",
+      "name": "kithara-studio-frontend",
       "version": "0.1.0",
       "dependencies": {
         "fuse.js": "^7.0.0",