test(golden): add sentinel template directories

Three sentinel cases (SAM, CFN, LE-foreach) used by the harness in the
next commit. Each case carries metadata.yaml + README.md + src/app.py.
Pinned outputs (expected.*.yaml) are generated by update_goldens.py
once the harness is in place.

Author: bnusunny

tests/golden/__init__.py

@@ -0,0 +1,7 @@
+# foreach_static_zip
+
+Sentinel LE case. `Fn::ForEach` over a static collection with all expanded
+functions sharing the same `CodeUri`. Locks the expanded-template shape
+(`AlphaFunction`, `BetaFunction` inlined as siblings, ForEach key gone)
+and the post-package shape (each function's `CodeUri` rewritten to the
+same `s3://golden-bucket/<sha256>`).

tests/golden/templates/language_extensions/foreach_static_zip/README.md

@@ -0,0 +1,3 @@
+language_extensions: true
+description: "Sentinel: Fn::ForEach over static collection, shared CodeUri."
+issue_refs: []

tests/golden/templates/language_extensions/foreach_static_zip/metadata.yaml

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+def handler(event, context):
+    return {"ok": True}

tests/golden/templates/language_extensions/foreach_static_zip/src/app.py

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+AWSTemplateFormatVersion: '2010-09-09'
+Transform:
+  - AWS::LanguageExtensions
+  - AWS::Serverless-2016-10-31
+
+Resources:
+  Fn::ForEach::Workers:
+    - WorkerName
+    - - Alpha
+      - Beta
+    - ${WorkerName}Function:
+        Type: AWS::Serverless::Function
+        Properties:
+          Handler: app.handler
+          Runtime: python3.11
+          CodeUri: ./src/

tests/golden/templates/language_extensions/foreach_static_zip/template.yaml

@@ -0,0 +1,5 @@
+# lambda_function_zip
+
+Sentinel non-SAM case. Raw `AWS::Lambda::Function` with `Code: ./src/`. Locks
+the post-package output shape after the CFN-resource-list packageable walker
+rewrites `Code` to `s3://golden-bucket/<sha256>`.

tests/golden/templates/packageable_resources/lambda_function_zip/README.md

@@ -0,0 +1,3 @@
+language_extensions: false
+description: "Sentinel: raw AWS::Lambda::Function with local Code path."
+issue_refs: []

tests/golden/templates/packageable_resources/lambda_function_zip/metadata.yaml

@@ -0,0 +1,2 @@
+def handler(event, context):
+    return {"ok": True}

tests/golden/templates/packageable_resources/lambda_function_zip/src/app.py

@@ -0,0 +1,12 @@
+AWSTemplateFormatVersion: '2010-09-09'
+
+Resources:
+  HelloFunction:
+    Type: AWS::Lambda::Function
+    Properties:
+      FunctionName: hello
+      Runtime: python3.11
+      Handler: app.handler
+      Role: arn:aws:iam::123456789012:role/lambda-role
+      Code: ./src/
+      MemorySize: 128

tests/golden/templates/packageable_resources/lambda_function_zip/template.yaml

@@ -0,0 +1,6 @@
+# serverless_function_zip
+
+Sentinel SAM case. Vanilla `AWS::Serverless::Function` with local `CodeUri`
+pointing at a ZIP-packaged source dir. Locks the post-build `template.yaml`
+shape (artifact path normalized to `<<BUILT_ARTIFACT>>`) and post-package
+shape (CodeUri rewritten to `s3://golden-bucket/<sha256>`).