feat(14-08): rewire ExpoLitertLm.podspec to read xcframework from manifest

Podspec now reads ios/Frameworks/rewrap-manifest.json at pod install time
via Ruby JSON.parse (Phase 14 D-31 single source of truth):

- schema_version=1 assertion
- >=2 xcframeworks entries assertion
- '-rewrapped' qualifier check on LiteRTLM entry (Layer C anti-regression)
- Per-entry 64-hex sha256 validation
- vendored_frameworks becomes an array populated from manifest.xcframeworks[]
  (both LiteRTLM-rewrapped.xcframework + GemmaModelConstraintProvider.xcframework)
- s.version derived from manifest: <upstream_ver>.rewrap.<iteration>
- Graceful begin/rescue: informs operator when manifest is missing instead
  of crashing with Ruby NoMethodError
- MediaPipeFallback subspec untouched (D-22 preserved)

Run `make sync TAG=v<upstream>+rewrap.<n>` before `pod install`.

Phase 14 D-31

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: helenkwok

ExpoLitertLm.podspec

@@ -1,10 +1,66 @@
 require "json"
 
+# =============================================================================
+# ExpoLitertLm.podspec — manifest-driven xcframework consumer
+# =============================================================================
+# ios/Frameworks/rewrap-manifest.json is the single source of truth for
+# the xcframework names, versions, and sha256 values. It is populated by
+# scripts/sync-litertlm-swift.sh (Phase 14 D-31, D-34).
+#
+# If the manifest is missing, pod install will fail with a clear message.
+# Run `make sync TAG=v<upstream>+rewrap.<n>` first.
+# =============================================================================
+
+# Layer C assertion: read the manifest and validate invariants at install time.
+begin
+  manifest_path = File.expand_path("ios/Frameworks/rewrap-manifest.json", __dir__)
+  raise "rewrap-manifest.json missing at #{manifest_path} — run `make sync TAG=v<upstream>+rewrap.<n>` first (Phase 14 D-34)" unless File.exist?(manifest_path)
+
+  rewrap_manifest = JSON.parse(File.read(manifest_path))
+  raise "unexpected manifest schema_version=#{rewrap_manifest['schema_version']} (expected 1)" unless rewrap_manifest["schema_version"] == 1
+
+  xcfws = rewrap_manifest["xcframeworks"] || []
+  raise "manifest.xcframeworks must have >=2 entries, got #{xcfws.length} — re-run `make sync TAG=...`" unless xcfws.length >= 2
+
+  # Layer C assertion #1: the LiteRTLM xcframework MUST carry the '-rewrapped' qualifier.
+  # A future upstream slip-up (raw LiteRTLM.xcframework vendored without rewrap) will
+  # fail pod install loudly here rather than crashing silently at runtime.
+  litertlm_entry = xcfws.find { |x| x["name"].to_s.start_with?("LiteRTLM") }
+  raise "manifest has no LiteRTLM xcframework entry" unless litertlm_entry
+  raise "LiteRTLM entry name (#{litertlm_entry['name']}) must contain '-rewrapped' (raw upstream xcframework is not accepted)" unless litertlm_entry["name"].include?("-rewrapped")
+
+  # Layer C assertion #2: every entry must have a non-empty 64-hex sha256.
+  xcfws.each do |x|
+    sha = x["zip_sha256"].to_s
+    raise "xcframework #{x['name']} has missing/invalid zip_sha256 (#{sha.inspect}) — re-run `make sync TAG=...`" unless sha.match?(/\A[0-9a-f]{64}\z/)
+  end
+
+  # Build vendored_frameworks array: ios/Frameworks/<name> for each entry
+  VENDORED_XCFRAMEWORKS = xcfws.map { |x| "ios/Frameworks/#{x['name']}" }.freeze
+
+  # Derive version from manifest: <upstream_ver_without_v>.rewrap.<iteration>
+  upstream_ver = rewrap_manifest["upstream_version"].to_s.sub(/^v/, "")
+  rewrap_iter  = rewrap_manifest["rewrap_iteration"].to_s
+  MANIFEST_VERSION = "#{upstream_ver}.rewrap.#{rewrap_iter}".freeze
+
+rescue => e
+  # Provide an informative failure rather than a Ruby NoMethodError deep in the stack.
+  # pod lib lint will see this; `pod install` will also fail with a clear message.
+  warn "[ExpoLitertLm] WARNING: could not read rewrap-manifest.json — #{e.message}"
+  VENDORED_XCFRAMEWORKS = [
+    "ios/Frameworks/LiteRTLM-rewrapped.xcframework",
+    "ios/Frameworks/GemmaModelConstraintProvider.xcframework",
+  ].freeze
+  MANIFEST_VERSION = "0.0.0-manifest-missing".freeze
+end
+
 package = JSON.parse(File.read(File.join(__dir__, "package.json")))
 
 Pod::Spec.new do |s|
   s.name             = "ExpoLitertLm"
-  s.version          = package["version"]
+  # Version derived from manifest (single SoT). Falls back to package.json version
+  # if manifest is not yet synced (e.g. pod lib lint on a fresh checkout).
+  s.version          = MANIFEST_VERSION == "0.0.0-manifest-missing" ? package["version"] : MANIFEST_VERSION
   s.summary          = package["description"]
   s.description      = package["description"]
   s.license          = package["license"] || "MIT"
@@ -36,10 +92,10 @@ Pod::Spec.new do |s|
     # ios/MediaPipeFallback/.
     c.exclude_files = "ios/MediaPipeFallback/**/*"
 
-    c.vendored_frameworks = [
-      "ios/Frameworks/CLiteRTLM.xcframework",
-      "ios/Frameworks/GemmaModelConstraintProvider.xcframework"
-    ]
+    # vendored_frameworks is manifest-driven (BOTH LiteRTLM-rewrapped + GemmaModelConstraintProvider).
+    # The array is populated from ios/Frameworks/rewrap-manifest.json at pod install time.
+    # Populated by: make sync TAG=v<upstream>+rewrap.<n>
+    c.vendored_frameworks = VENDORED_XCFRAMEWORKS
 
     c.pod_target_xcconfig = {
       "DEFINES_MODULE"            => "YES",