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.

app.config.js

@@ -1,3 +1,41 @@
+const { execFileSync } = require("node:child_process");
+
+// Build metadata, injected into `extra.build` and read at runtime via
+// expo-constants (see utils/version.ts). Sources in priority order:
+// EAS cloud build → GitHub Actions → explicit EXPO_PUBLIC_* → local git → null.
+const git = (args) => {
+  try {
+    return execFileSync("git", args, { stdio: ["ignore", "pipe", "ignore"] })
+      .toString()
+      .trim();
+  } catch {
+    return null;
+  }
+};
+
+const buildMeta = {
+  commit:
+    (
+      process.env.EAS_BUILD_GIT_COMMIT_HASH ||
+      process.env.GITHUB_SHA ||
+      process.env.EXPO_PUBLIC_GIT_COMMIT ||
+      git(["rev-parse", "HEAD"]) ||
+      ""
+    ).slice(0, 7) || null,
+  branch:
+    process.env.EAS_BUILD_GIT_BRANCH ||
+    process.env.GITHUB_HEAD_REF ||
+    process.env.GITHUB_REF_NAME ||
+    process.env.EXPO_PUBLIC_GIT_BRANCH ||
+    git(["rev-parse", "--abbrev-ref", "HEAD"]) ||
+    null,
+  profile:
+    process.env.EAS_BUILD_PROFILE ||
+    process.env.EXPO_PUBLIC_BUILD_PROFILE ||
+    null,
+  builtAt: new Date().toISOString(),
+};
+
 module.exports = ({ config }) => {
   if (process.env.EXPO_TV !== "1") {
     config.plugins.push("expo-background-task");
@@ -22,6 +60,8 @@ module.exports = ({ config }) => {
     androidConfig.googleServicesFile = process.env.GOOGLE_SERVICES_JSON;
   }
 
+  config.extra = { ...config.extra, build: buildMeta };
+
   return {
     ...(Object.keys(androidConfig).length > 0 && { android: androidConfig }),
     ...config,