Unlock everything, add a donation link, credit Last.fm, nudge re-linking

- Every feature is free for everyone (the plan system stays for later);
  remaining limits are abuse guards
- Optional website donation link (NEXT_PUBLIC_DONATION_URL). Not shown in
  the mobile apps, where tips to the developer generally need in-app
  purchase
- Last.fm/ListenBrainz-sourced plays link to the user's profile, as
  Last.fm's API terms require
- Connections track when they last saw activity; a scrobbler silent for
  over a week prompts re-linking Spotify (its link expires every 6 months)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MzFywujuH9TiuXbr9vjoX8

apps/api/src/services/connections.ts

@@ -14,6 +14,7 @@ export const toConnectionDTO = (c: Connection): ConnectionDTO => ({
   status: c.status,
   lastError: c.lastError,
   lastPolledAt: c.lastPolledAt?.toISOString() ?? null,
+  lastActivityAt: c.lastActivityAt?.toISOString() ?? null,
   webhookUrl: c.webhookSecret ? `${env.API_PUBLIC_URL}/webhooks/${c.provider}/${c.webhookSecret}` : null,
 });
 

apps/api/src/services/nowPlaying.ts

@@ -33,6 +33,7 @@ export async function getNowPlaying(userIds: string[]): Promise<NowPlayingDTO[]>
       isPlaying: np.isPlaying && !(PUSH_SOURCES.has(np.source) && Date.now() - np.updatedAt.getTime() > DEVICE_STALE_MS),
       source: np.source,
       sourceApp: np.sourceApp,
+      sourceUrl: np.sourceUrl,
       progressMs: np.progressMs,
       updatedAt: np.updatedAt.toISOString(),
     }))
@@ -96,7 +97,7 @@ export async function applyPollResult(
   userId: string,
   source: NowPlayingProvider,
   result: PollResult | null,
-  opts: { sourceApp?: string | null } = {},
+  opts: { sourceApp?: string | null; sourceUrl?: string | null } = {},
 ): Promise<boolean> {
   const [current] = await db.select().from(schema.nowPlaying).where(eq(schema.nowPlaying.userId, userId));
   const now = new Date();
@@ -122,6 +123,7 @@ export async function applyPollResult(
     trackId: track.id,
     source,
     sourceApp: opts.sourceApp ?? null,
+    sourceUrl: opts.sourceUrl ?? null,
     isPlaying: true,
     progressMs: result.progressMs,
     updatedAt: now,