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

backend/src/main.py

@@ -6,18 +6,18 @@ import os
 import shutil
 from dotenv import load_dotenv
 
-# Load environment variables BEFORE importing lyria_client (it reads env at module level)
+# Load environment variables BEFORE importing kithara_client (it reads env at module level)
 load_dotenv(Path(__file__).parent.parent / ".env")
 
 from models import GenerateRequest, GenerateResponse, ClipList, RenameRequest, MetadataRequest, GenerateArtworkRequest, LYRIA_MODELS, DEFAULT_MODEL
 from database import init_db, create_clip, get_clips, get_clip, delete_clip, update_clip_status, rename_clip, set_artwork, remove_artwork, delete_all_clips, set_analysis, update_metadata
-from lyria_client import generate_clip, save_clip_file
+from kithara_client import generate_clip, save_clip_file
 from waveform import generate_waveform_svg, get_waveform_path
 from analysis import analyze_clip
 from image_gen import generate_artwork, get_image_gen_config, get_available_models, SAFETY_LEVELS
 from text_gen import suggest_prompts, get_text_gen_config, get_available_models as get_text_models
 
-app = FastAPI(title="Lyria Studio", version="0.1.0")
+app = FastAPI(title="Kithara Studio", version="0.1.0")
 
 app.add_middleware(
     CORSMiddleware,
@@ -49,7 +49,7 @@ async def list_models():
     return {"models": LYRIA_MODELS, "default": DEFAULT_MODEL}
 
 async def _generate_and_save(clip_id: str, prompt: str, model: str, duration: int):
-    """Background task: call Lyria API and save the result.
+    """Background task: call Google Lyria API and save the result.
     
     DR-LYRIA-001: Pre-generates waveform SVG after clip is ready,
     so users never wait for on-demand generation.