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/tailwind.config.js

@@ -7,12 +7,12 @@ export default {
   theme: {
     extend: {
       colors: {
-        'lyria-dark': '#0a0a0f',
-        'lyria-panel': '#12121a',
-        'lyria-surface': '#1a1a24',
-        'lyria-accent': '#ff6b35',
-        'lyria-text': '#e0e0e0',
-        'lyria-muted': '#6b6b7b',
+        'kithara-dark': '#0a0a0f',
+        'kithara-panel': '#12121a',
+        'kithara-surface': '#1a1a24',
+        'kithara-accent': '#ff6b35',
+        'kithara-text': '#e0e0e0',
+        'kithara-muted': '#6b6b7b',
       },
       keyframes: {
         'marquee-scroll': {