Add campaign layer, GPU model caching, file browser cleanup

- Campaigns: new table, CRUD API, React context + provider
- Sessions: scoped to campaigns, paths under campaigns/{id}/
- File browser: scoped per campaign, removed copy/paste/autoPlay
- Sidebar: campaign selector dropdown at top
- Transcribe: GPU model cached/released via job counter
- Jobs: status text updates dynamically in real-time
- Auto-redirect: blocked when summarize job is active

backend/app/database.py

@@ -86,6 +86,26 @@ def init_db():
                 updated_at REAL NOT NULL
             )
         """)
+        conn.execute("""
+            CREATE TABLE IF NOT EXISTS campaigns (
+                id TEXT PRIMARY KEY,
+                name TEXT NOT NULL,
+                description TEXT NOT NULL DEFAULT '',
+                created_at REAL NOT NULL
+            )
+        """)
+        try:
+            conn.execute("ALTER TABLE sessions ADD COLUMN campaign_id TEXT REFERENCES campaigns(id) ON DELETE SET NULL")
+        except Exception:
+            pass
+        default = conn.execute("SELECT id FROM campaigns WHERE id = 'default'").fetchone()
+        if not default:
+            conn.execute(
+                "INSERT INTO campaigns (id, name, description, created_at) VALUES (?, ?, '', ?)",
+                ("default", "Default Campaign", now()),
+            )
+            conn.execute("UPDATE sessions SET campaign_id = 'default' WHERE campaign_id IS NULL")
+
         # seed defaults if empty
         existing = {r["key"] for r in conn.execute("SELECT key FROM settings")}
         for k, v in config.DEFAULT_SETTINGS.items():
@@ -140,3 +160,47 @@ def update_job(job_id: str, **fields):
 def get_job(job_id: str) -> dict | None:
     row = get_conn().execute("SELECT * FROM jobs WHERE id = ?", (job_id,)).fetchone()
     return dict(row) if row else None
+
+def create_campaign(name: str, description: str = "") -> dict:
+    campaign_id = new_id()
+    with tx() as conn:
+        conn.execute(
+            "INSERT INTO campaigns (id, name, description, created_at) VALUES (?, ?, ?, ?)",
+            (campaign_id, name, description, now()),
+        )
+    from .config import campaign_audio_dir, campaign_transcript_dir, campaign_notes_dir
+    campaign_audio_dir(campaign_id).mkdir(parents=True, exist_ok=True)
+    campaign_transcript_dir(campaign_id).mkdir(parents=True, exist_ok=True)
+    campaign_notes_dir(campaign_id).mkdir(parents=True, exist_ok=True)
+    return get_campaign(campaign_id)
+
+def list_campaigns() -> list[dict]:
+    rows = get_conn().execute(
+        "SELECT c.*, (SELECT COUNT(*) FROM sessions s WHERE s.campaign_id = c.id) as session_count "
+        "FROM campaigns c ORDER BY c.created_at DESC"
+    ).fetchall()
+    return [dict(r) for r in rows]
+
+def get_campaign(campaign_id: str) -> dict | None:
+    row = get_conn().execute(
+        "SELECT c.*, (SELECT COUNT(*) FROM sessions s WHERE s.campaign_id = c.id) as session_count "
+        "FROM campaigns c WHERE c.id = ?", (campaign_id,)
+    ).fetchone()
+    return dict(row) if row else None
+
+def update_campaign(campaign_id: str, name: str | None = None, description: str | None = None) -> dict | None:
+    fields = {}
+    if name is not None: fields["name"] = name
+    if description is not None: fields["description"] = description
+    if not fields:
+        return get_campaign(campaign_id)
+    with tx() as conn:
+        cols = ", ".join(f"{k} = ?" for k in fields)
+        conn.execute(f"UPDATE campaigns SET {cols} WHERE id = ?", (*fields.values(), campaign_id))
+    return get_campaign(campaign_id)
+
+def delete_campaign(campaign_id: str) -> bool:
+    with tx() as conn:
+        conn.execute("UPDATE sessions SET campaign_id = NULL WHERE campaign_id = ?", (campaign_id,))
+        conn.execute("DELETE FROM campaigns WHERE id = ?", (campaign_id,))
+    return True