feat(career): career plugin — stars, venue tiers, pack downloads (career mode 2/3) (#907)

* feat(career): career plugin — stars from song_stats, venue tiers, pack downloads (career mode PR2)

Bundled plugin: per-song stars from best_accuracy (60/75/85% → 1/2/3★),
cumulative stars unlock bar → club → arena (data-driven venues.json).
Venue packs (UE-rendered crowd loops) download on demand to
CONFIG_DIR/plugin_uploads/career/ on a background thread with sha256 +
zip-slip validation, served via FileResponse. Career screen (promoted
sidebar entry) shows progress and pushes the active venue's manifest
into the crowd video layer (v3VenueCrowd, PR1) — degrades cleanly when
either side is absent. Pack URLs land in venues.json in PR3.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(career): keep manifest cleanup path alive on delete; badge only for installed venues

Codex preflight: nulling _appliedManifestVenue on delete skipped
pushCrowdManifest's setManifest(null) cleanup, leaving the crowd layer on
a deleted pack; and the 'playing here' badge showed for an override venue
whose pack was removed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(career): generation-guard in-flight manifest fetches

Codex preflight: a manifest fetch resolving after a newer refresh (pack
deleted, venue switched) could re-apply a stale pack over the user's
newer selection — fetches now carry a generation token and bail when
superseded.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(career): exclude orphaned song_stats from star totals

Codex preflight: scans hide rather than delete stats of removed songs, so
stars now apply the same existing-song filter other stats surfaces use
(filename IN (SELECT filename FROM songs)).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(career): 50/150 star thresholds + star collection overview

Byron's progression tuning: club at 50★, arena at 150★. /state now
returns star_detail rows (title/artist joined from the library, stars,
best accuracy, next-star threshold) sorted closest-to-next-star first,
and the career screen renders a collection panel: tier summary plus a
per-song list with a 'N% to next star' practice hint.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(career): venue select/unselect UX, intro manifest support, fullmatch guards

- 'Play here' now also defaults the visualization to Venue (remembering
  the prior viz); active venues show 'Leave venue' which restores it and
  sets the '__none__' override so no installed venue silently reapplies.
- Pack manifests may ship an intro block (flyover video + ambience mp3);
  files validate like loops/stingers, .mp3 added to the serving whitelist.
- Codex preflight: whitelist regexes use fullmatch (trailing-newline names
  could validate but 500 on serving).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(career): let pushCrowdManifest clear the manifest on Leave venue

Codex preflight: nulling _appliedManifestVenue before refresh skipped the
setManifest(null) cleanup branch, leaving the crowd playing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(career): refresh tailwind output

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

static/v3/shell.js

@@ -48,6 +48,7 @@
         // above. Screens are injected async by the plugin loader, so go()'s
         // plugin- guard applies.
         { key: 'virtuoso',    screen: 'plugin-virtuoso',    label: 'Virtuoso - Practice', group: null, icon: 'target' },
+        { key: 'career',      screen: 'plugin-career',      label: 'Career',      group: null,      icon: 'trophy' },
         { key: 'rig_builder', screen: 'plugin-rig_builder', label: 'Rig Builder', group: null,      icon: 'amp' },
         { key: 'editor',      screen: 'plugin-editor',      label: 'Song Editor', group: null,      icon: 'edit' },
         { key: 'audio_engine', screen: 'plugin-audio_engine', label: 'Audio', group: null,        icon: 'amp' },
@@ -60,6 +61,7 @@
     // that group. Each is gated on the plugin actually being installed.
     const PROMOTED_PLUGINS = [
         { navKey: 'virtuoso',    pluginId: 'virtuoso',    slotId: 'v3-nav-virtuoso',    anchorAfter: 'feedbarcade' },
+        { navKey: 'career',      pluginId: 'career',      slotId: 'v3-nav-career',      anchorAfter: 'feedbarcade' },
         { navKey: 'rig_builder', pluginId: 'rig_builder', slotId: 'v3-nav-rig-builder', anchorAfter: 'saved' },
         { navKey: 'editor',      pluginId: 'editor',      slotId: 'v3-nav-editor',     anchorAfter: 'songs' },
         { navKey: 'audio_engine', pluginId: 'audio_engine', slotId: 'v3-nav-audio-engine', anchorAfter: 'settings' },