Flatpak: build from source instead of repackaging debs

- Rewrite Flatpak manifest to build from source using SDK extensions
  (node22, rust-stable) with offline cargo/npm dependency caches
- Add generate-sources.sh to produce cargo-sources.json and
  node-sources.json from lock files using flatpak-builder-tools
- Vendor Node.js, protoc, and wasm-pack as archive sources with
  SHA256 verification and per-arch support
- Add SHA256 verification to vendor-node.cjs and vendor-protoc.cjs
- Rewrite update-manifest.sh to update git tag/commit and regenerate
  dependency sources
- Update Flathub CI workflow to install generators and copy source
  files
- Remove stale plugins/faker entry from package-lock.json

scripts/vendor-node.cjs

@@ -1,4 +1,6 @@
 const path = require('node:path');
+const crypto = require('node:crypto');
+const fs = require('node:fs');
 const decompress = require('decompress');
 const Downloader = require('nodejs-file-downloader');
 const { rmSync, cpSync, mkdirSync, existsSync } = require('node:fs');
@@ -41,6 +43,15 @@ const DST_BIN_MAP = {
   [WIN_ARM]: 'yaaknode.exe',
 };
 
+const SHA256_MAP = {
+  [MAC_ARM]: 'b05aa3a66efe680023f930bd5af3fdbbd542794da5644ca2ad711d68cbd4dc35',
+  [MAC_X64]: '096081b6d6fcdd3f5ba0f5f1d44a47e83037ad2e78eada26671c252fe64dd111',
+  [LNX_ARM]: '0dc93ec5c798b0d347f068db6d205d03dea9a71765e6a53922b682b91265d71f',
+  [LNX_X64]: '58a5ff5cc8f2200e458bea22e329d5c1994aa1b111d499ca46ec2411d58239ca',
+  [WIN_X64]: '5355ae6d7c49eddcfde7d34ac3486820600a831bf81dc3bdca5c8db6a9bb0e76',
+  [WIN_ARM]: 'ce9ee4e547ebdff355beb48e309b166c24df6be0291c9eaf103ce15f3de9e5b4',
+};
+
 const key = `${process.platform}_${process.env.YAAK_TARGET_ARCH ?? process.arch}`;
 
 const destDir = path.join(__dirname, `..`, 'crates-tauri', 'yaak-app', 'vendored', 'node');
@@ -68,6 +79,15 @@ rmSync(tmpDir, { recursive: true, force: true });
     timeout: 1000 * 60 * 2,
   }).download();
 
+  // Verify SHA256
+  const expectedHash = SHA256_MAP[key];
+  const fileBuffer = fs.readFileSync(filePath);
+  const actualHash = crypto.createHash('sha256').update(fileBuffer).digest('hex');
+  if (actualHash !== expectedHash) {
+    throw new Error(`SHA256 mismatch for ${path.basename(filePath)}\n  expected: ${expectedHash}\n  actual:   ${actualHash}`);
+  }
+  console.log('SHA256 verified:', actualHash);
+
   // Decompress to the same directory
   await decompress(filePath, tmpDir, {});