Add paste-your-songs manual import feature

Users can now paste a list of songs as text to create a playlist without
needing any service integration. Supports multiple formats: "Artist - Title",
"Title by Artist", "Artist: Title", and numbered lists. Includes a live
song count preview in the modal and free tier playlist limit enforcement.

backend/app/api/endpoints/manual_import.py

@@ -0,0 +1,112 @@
+import re
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.config import settings
+from app.core.database import get_db
+from app.core.security import get_current_user
+from app.models.user import User
+from app.models.playlist import Playlist
+from app.models.track import Track
+from app.services.recommender import build_taste_profile
+from app.schemas.playlist import PlaylistDetailResponse
+
+router = APIRouter(prefix="/import", tags=["import"])
+
+
+class PasteImportRequest(BaseModel):
+    name: str
+    text: str
+
+
+def parse_song_line(line: str) -> dict | None:
+    line = line.strip()
+    if not line:
+        return None
+
+    # Strip leading numbering: "1.", "2)", "1 -", "01.", etc.
+    line = re.sub(r"^\d+[\.\)\-\:]\s*", "", line).strip()
+    if not line:
+        return None
+
+    # Try "Artist - Title" (most common)
+    if " - " in line:
+        parts = line.split(" - ", 1)
+        return {"artist": parts[0].strip(), "title": parts[1].strip()}
+
+    # Try "Title by Artist"
+    if " by " in line.lower():
+        idx = line.lower().index(" by ")
+        return {"title": line[:idx].strip(), "artist": line[idx + 4 :].strip()}
+
+    # Try "Artist: Title"
+    if ": " in line:
+        parts = line.split(": ", 1)
+        return {"artist": parts[0].strip(), "title": parts[1].strip()}
+
+    # Fallback: treat whole line as title with unknown artist
+    return {"title": line, "artist": "Unknown"}
+
+
+@router.post("/paste", response_model=PlaylistDetailResponse)
+async def import_pasted_songs(
+    data: PasteImportRequest,
+    user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    if not data.name.strip():
+        raise HTTPException(status_code=400, detail="Playlist name is required")
+    if not data.text.strip():
+        raise HTTPException(status_code=400, detail="No songs provided")
+
+    # Free tier limit
+    if not user.is_pro:
+        result = await db.execute(
+            select(Playlist).where(Playlist.user_id == user.id)
+        )
+        existing = list(result.scalars().all())
+        if len(existing) >= settings.FREE_MAX_PLAYLISTS:
+            raise HTTPException(
+                status_code=403,
+                detail="Free tier limited to 1 playlist. Upgrade to Pro for unlimited.",
+            )
+
+    # Parse lines
+    lines = data.text.strip().splitlines()
+    parsed = [parse_song_line(line) for line in lines]
+    parsed = [p for p in parsed if p is not None]
+
+    if not parsed:
+        raise HTTPException(status_code=400, detail="Could not parse any songs from the text")
+
+    # Create playlist
+    playlist = Playlist(
+        user_id=user.id,
+        name=data.name.strip(),
+        platform_source="manual",
+        track_count=len(parsed),
+    )
+    db.add(playlist)
+    await db.flush()
+
+    # Create tracks
+    tracks = []
+    for p in parsed:
+        track = Track(
+            playlist_id=playlist.id,
+            title=p["title"],
+            artist=p["artist"],
+        )
+        db.add(track)
+        tracks.append(track)
+
+    await db.flush()
+
+    # Build taste profile
+    playlist.taste_profile = build_taste_profile(tracks)
+    playlist.tracks = tracks
+
+    return playlist