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>

tests/js/career_plugin.test.js

@@ -0,0 +1,50 @@
+'use strict';
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const ROOT = path.join(__dirname, '..', '..');
+const PLUGIN_DIR = path.join(ROOT, 'plugins', 'career');
+const SHELL_JS = path.join(ROOT, 'static', 'v3', 'shell.js');
+
+test('career plugin manifest is complete and bundled', () => {
+    const manifest = JSON.parse(fs.readFileSync(path.join(PLUGIN_DIR, 'plugin.json'), 'utf8'));
+    assert.equal(manifest.id, 'career');
+    assert.equal(manifest.bundled, true);
+    assert.equal(manifest.screen, 'screen.html');
+    assert.equal(manifest.script, 'screen.js');
+    assert.equal(manifest.routes, 'routes.py');
+    for (const f of ['screen.html', 'screen.js', 'routes.py', 'venues.json', manifest.styles]) {
+        assert.ok(fs.existsSync(path.join(PLUGIN_DIR, f)), `${f} missing`);
+    }
+});
+
+test('venues.json defines the 3 ascending tiers with star thresholds', () => {
+    const content = JSON.parse(fs.readFileSync(path.join(PLUGIN_DIR, 'venues.json'), 'utf8'));
+    assert.deepEqual(content.star_accuracy_thresholds, [0.6, 0.75, 0.85]);
+    const venues = content.venues;
+    assert.deepEqual(venues.map((v) => v.id), ['bar', 'club', 'arena']);
+    assert.equal(venues[0].star_threshold, 0, 'bar must always be unlocked');
+    for (let i = 1; i < venues.length; i++) {
+        assert.ok(venues[i].star_threshold > venues[i - 1].star_threshold,
+            'thresholds must ascend');
+    }
+});
+
+test('shell promotes the career plugin into the sidebar', () => {
+    const src = fs.readFileSync(SHELL_JS, 'utf8');
+    assert.match(src, /key: 'career',\s*screen: 'plugin-career'/);
+    assert.match(src, /navKey: 'career',\s*pluginId: 'career',\s*slotId: 'v3-nav-career'/);
+});
+
+test('career screen pushes the crowd manifest with a base URL', () => {
+    const src = fs.readFileSync(path.join(PLUGIN_DIR, 'screen.js'), 'utf8');
+    assert.match(src, /v3VenueCrowd/);
+    assert.match(src, /setManifest\(manifest\)/);
+    assert.match(src, /manifest\.base = /);
+    assert.match(src, /feedBack-career-venue/);
+    // Degrades without the crowd layer (PR1 not merged / older desktop).
+    assert.match(src, /typeof crowd\.setManifest !== 'function'\) return/);
+});