feat(settings): Open Source Licenses section in System tab (#477)

* feat(licenses): tooling and initial data generation

Adds the maintainer-only generator that produces src/data/licenses.json:
- src-tauri/about.toml + about.hbs: cargo-about config + handlebars template
  for the Rust-side license enumeration
- scripts/generate-licenses.mjs: orchestrator that runs cargo-about and
  license-checker-rseidelsohn (via npx, no devDep), merges the outputs into
  a single per-crate JSON with full license texts, and writes the result to
  src/data/licenses.json

The script is invoked directly with `node scripts/generate-licenses.mjs` —
no npm script wrapper on purpose, since adding one to package.json would
trigger the nix-npm-deps-hash-sync workflow on every push.

Initial generation covers 575 cargo crates + 71 npm packages (646 entries
total, all with full license text bundled, ~1.4 MB JSON).

* feat(licenses): Settings panel UI

Adds a new Open Source Licenses section under Settings → System,
sitting below Contributors. Components:

- LicensesPanel.tsx: search input, curated highlight block of ~10 key
  dependencies (Tauri, React, rodio, symphonia, etc.), TanStack-Virtual
  list of all 600+ entries
- LicenseTextModal.tsx: full-screen-ish modal showing the bundled license
  text plus name/version/license-id badges + repository link
- licensesData.ts: lazy dynamic-import loader (Vite emits the JSON as a
  separate chunk, so the heavy ~1.4 MB payload is only loaded when the
  user actually opens the panel — no runtime fetch, the data is fixed
  into the build artifact)

The panel registers itself in the Settings in-page search index under
the System tab.

* feat(licenses): i18n in 8 locales

Adds the `licenses` namespace (title, intro, highlights, search
placeholder, no-results, loading / load error, no-license-text,
view-source, total line, generated-at) across en, de, fr, nl, zh, nb,
ru, es. License names themselves (MIT, Apache-2.0, GPL-3.0, …) stay
universal and are rendered as-is.

* docs(release): document licenses regeneration step

Adds a Step A.3 to the release SOP describing the maintainer-only
`node scripts/generate-licenses.mjs` workflow, the cargo-about
prerequisite, and explicitly notes why no npm script wrapper exists
(would trigger the nix-npm-deps-hash-sync workflow).

src/pages/Settings.tsx

@@ -6,7 +6,7 @@ import {
   Wifi, WifiOff, Globe, Music2, Sliders, LogOut, CheckCircle2, FolderOpen,
   Palette, Server, Plus, Trash2, Eye, EyeOff, Info, ExternalLink, Shuffle, X, Play, Type, Keyboard, ChevronDown,
   GripVertical, PanelLeft, RotateCcw, LayoutGrid, AppWindow, HardDrive, Upload, Download, Waves, Star, Clock, ZoomIn, Sparkles, AlertTriangle, Maximize2, AudioLines, User, Lock,
-  Users, UserPlus, Shield, Wand2, Search
+  Users, UserPlus, Shield, Wand2, Search, Scale
 } from 'lucide-react';
 import i18n from '../i18n';
 import { exportBackup, importBackup } from '../utils/backup';
@@ -22,6 +22,7 @@ import { lastfmGetToken, lastfmAuthUrl, lastfmGetSession, lastfmGetUserInfo, Las
 import LastfmIcon from '../components/LastfmIcon';
 import CustomSelect from '../components/CustomSelect';
 import SettingsSubSection from '../components/SettingsSubSection';
+import LicensesPanel from '../components/LicensesPanel';
 import { AboutPsysonicBrandHeader } from '../components/AboutPsysonicLol';
 import { useLuckyMixAvailable } from '../hooks/useLuckyMixAvailable';
 import ThemePicker, { THEME_GROUPS } from '../components/ThemePicker';
@@ -439,6 +440,7 @@ const SETTINGS_INDEX: SearchIndexEntry[] = [
   { tab: 'system',         titleKey: 'settings.loggingTitle',             keywords: 'log logs diagnostic debug verbose' },
   { tab: 'system',         titleKey: 'settings.aboutTitle',               keywords: 'about version update changelog release notes' },
   { tab: 'system',         titleKey: 'settings.aboutContributorsLabel',   keywords: 'contributors credits maintainers' },
+  { tab: 'system',         titleKey: 'licenses.title',                    keywords: 'licenses license open source attribution copyright third party dependencies oss' },
 ];
 
 // Substring-first, Fuzzy-Fallback (alle Query-Zeichen in Reihenfolge im
@@ -4574,6 +4576,13 @@ export default function Settings() {
             </div>
           </SettingsSubSection>
 
+          <SettingsSubSection
+            title={t('licenses.title')}
+            icon={<Scale size={16} />}
+          >
+            <LicensesPanel />
+          </SettingsSubSection>
+
         </>
       )}
       </>}