feat(settings): graduated version tracking + Jellyfin clientInfo auto-sync

Settings "App version" now shows a graduated build identifier (utils/version.ts,
read defensively so it never crashes the screen):
- dev / local            -> "0.54.1 - branch - commit"
- develop / CI / preview  -> "0.54.1 - commit"
- production (store/TestFlight) -> "0.54.1 (42)"

app.config.js injects extra.build {commit, branch, profile, builtAt} from
EAS_BUILD_* / GITHUB_* / local git; build-apps.yml passes the PR branch+commit.
JellyfinProvider now sends APP_VERSION (auto-synced from expo-application) in its
clientInfo/auth header instead of a hardcoded "0.54.1". Version scheme unchanged.

utils/version.ts

@@ -0,0 +1,86 @@
+import * as Application from "expo-application";
+import Constants from "expo-constants";
+
+/** Raw marketing version (app.json `version`), e.g. "0.54.1". Exposed so the Jellyfin
+ * clientInfo auto-tracks the app version instead of a hardcoded string. */
+export const APP_VERSION = Application.nativeApplicationVersion ?? "unknown";
+
+/** Build metadata injected at build time by `app.config.js` into `extra.build`. */
+export interface BuildMeta {
+  commit?: string | null;
+  branch?: string | null;
+  profile?: string | null;
+  builtAt?: string | null;
+}
+
+export interface VersionInfo {
+  /** Marketing version (CFBundleShortVersionString / android versionName), e.g. "0.54.1". */
+  version: string | null;
+  /** Build number (CFBundleVersion / versionCode), e.g. "42". */
+  build: string | null;
+  /** Short git commit the build was made from, e.g. "a1b2c3d". */
+  commit: string | null;
+  /** Git branch the build was made from, e.g. "develop". */
+  branch: string | null;
+  /** EAS build profile, e.g. "production", "preview", or null for local. */
+  profile: string | null;
+  isDev: boolean;
+  isProduction: boolean;
+  /** Graduated label for the Settings "App version" row (see tiering below). */
+  display: string;
+}
+
+/**
+ * Resolve a graduated version string for Settings.
+ *
+ * Tiering (most → least detailed):
+ *  - dev / local build   → `version · branch · commit`   (full context for debugging)
+ *  - develop / CI / preview → `version · commit`          (pin the exact source)
+ *  - production (store / TestFlight) → `version (build)`   (store-correlatable; the
+ *      build number lets TestFlight reports pin a build whose version isn't a
+ *      published release. Note: TestFlight and the public App Store ship the same
+ *      binary — telling them apart needs a runtime iOS receipt check, intentionally
+ *      not done here.)
+ */
+export function getVersionInfo(): VersionInfo {
+  // Read native/config values defensively — a version string must never crash Settings
+  // (e.g. a dev build whose native expo-constants is out of sync with the JS).
+  const read = <T>(fn: () => T): T | null => {
+    try {
+      return fn() ?? null;
+    } catch {
+      return null;
+    }
+  };
+
+  const version = read(() => Application.nativeApplicationVersion);
+  const build = read(() => Application.nativeBuildVersion);
+  const meta = (read(() => Constants.expoConfig?.extra?.build) ??
+    {}) as BuildMeta;
+  const commit = meta.commit ?? null;
+  const branch = meta.branch ?? null;
+  const profile = meta.profile ?? null;
+  const isDev = __DEV__ === true;
+  const isProduction =
+    typeof profile === "string" && profile.startsWith("production");
+
+  let display: string;
+  if (isDev) {
+    display = [version ?? "dev", branch, commit].filter(Boolean).join(" · ");
+  } else if (isProduction) {
+    display = build ? `${version} (${build})` : (version ?? "N/A");
+  } else {
+    display = [version, commit].filter(Boolean).join(" · ") || version || "N/A";
+  }
+
+  return {
+    version,
+    build,
+    commit,
+    branch,
+    profile,
+    isDev,
+    isProduction,
+    display,
+  };
+}