Add playlist export and SEO meta tags

Add text/CSV export endpoints for playlists and saved recommendations.
Add export buttons to PlaylistDetail and Recommendations pages.
Add Open Graph and Twitter meta tags to index.html for better SEO.

backend/app/api/endpoints/playlists.py

@@ -1,4 +1,5 @@
-from fastapi import APIRouter, Depends, HTTPException
+from fastapi import APIRouter, Depends, HTTPException, Query
+from fastapi.responses import PlainTextResponse
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import selectinload
@@ -49,6 +50,39 @@ async def get_playlist(
     return playlist
 
 
+@router.get("/{playlist_id}/export")
+async def export_playlist(
+    playlist_id: int,
+    format: str = Query("text", pattern="^(text|csv)$"),
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    result = await db.execute(
+        select(Playlist).options(selectinload(Playlist.tracks))
+        .where(Playlist.id == playlist_id, Playlist.user_id == user.id)
+    )
+    playlist = result.scalar_one_or_none()
+    if not playlist:
+        raise HTTPException(status_code=404, detail="Playlist not found")
+
+    if format == "csv":
+        lines = ["Title,Artist,Album"]
+        for t in playlist.tracks:
+            # Escape commas in CSV
+            title = f'"{t.title}"' if ',' in t.title else t.title
+            artist = f'"{t.artist}"' if ',' in t.artist else t.artist
+            album = f'"{t.album}"' if t.album and ',' in t.album else (t.album or '')
+            lines.append(f"{title},{artist},{album}")
+        return PlainTextResponse("\n".join(lines), media_type="text/csv",
+            headers={"Content-Disposition": f'attachment; filename="{playlist.name}.csv"'})
+    else:
+        lines = [f"{playlist.name}", "=" * len(playlist.name), ""]
+        for i, t in enumerate(playlist.tracks, 1):
+            lines.append(f"{i}. {t.artist} - {t.title}")
+        return PlainTextResponse("\n".join(lines), media_type="text/plain",
+            headers={"Content-Disposition": f'attachment; filename="{playlist.name}.txt"'})
+
+
 @router.delete("/{playlist_id}")
 async def delete_playlist(
     playlist_id: int,

backend/app/api/endpoints/recommendations.py

@@ -1,9 +1,13 @@
 import hashlib
 import json
+import logging
 from urllib.parse import quote_plus
 
 import anthropic
+
+api_logger = logging.getLogger("app")
 from fastapi import APIRouter, Depends, HTTPException
+from fastapi.responses import PlainTextResponse
 from pydantic import BaseModel
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -77,6 +81,24 @@ async def history(
     return result.scalars().all()
 
 
+@router.get("/saved/export")
+async def export_saved(user: User = Depends(get_current_user), db: AsyncSession = Depends(get_db)):
+    result = await db.execute(
+        select(Recommendation).where(Recommendation.user_id == user.id, Recommendation.saved == True)
+        .order_by(Recommendation.created_at.desc())
+    )
+    recs = result.scalars().all()
+    lines = ["My Saved Discoveries - Vynl", "=" * 30, ""]
+    for i, r in enumerate(recs, 1):
+        lines.append(f"{i}. {r.artist} - {r.title}")
+        if r.youtube_url:
+            lines.append(f"   {r.youtube_url}")
+        lines.append(f"   {r.reason}")
+        lines.append("")
+    return PlainTextResponse("\n".join(lines), media_type="text/plain",
+        headers={"Content-Disposition": 'attachment; filename="vynl-discoveries.txt"'})
+
+
 @router.get("/saved", response_model=list[RecommendationItem])
 async def saved(
     user: User = Depends(get_current_user),
@@ -132,6 +154,12 @@ Return ONLY the JSON object."""
         messages=[{"role": "user", "content": prompt}],
     )
 
+    # Track API cost (Haiku: $0.80/M input, $4/M output)
+    input_tokens = message.usage.input_tokens
+    output_tokens = message.usage.output_tokens
+    cost = (input_tokens * 0.80 / 1_000_000) + (output_tokens * 4 / 1_000_000)
+    api_logger.info(f"API_COST|model=claude-haiku|input={input_tokens}|output={output_tokens}|cost=${cost:.4f}|user={user.id}|endpoint=analyze")
+
     response_text = message.content[0].text.strip()
     if response_text.startswith("```"):
         response_text = response_text.split("\n", 1)[1]