Fix: reject malformed/truncated `${{ secrets.` expressions in `processExpressions` #37727

Job	Run time
validate-yaml	10s
update	34s
safe-outputs-conformance	12s
build-wasm	58s
build	2m 23s
test	1m 24s
Alpine Container Test	1m 8s
actions-build	31s
Build & Test on macos-latest	42s
audit	40s
lint-go	1m 45s
lint-js	27s
Integration Add Workflows	1m 34s
logs-token-check	0s
mcp-server-compile-test	30s
security	53s
Build & Test on windows-latest	1m 33s
bench	0s
fuzz	0s
Security Scan: ${{ matrix.tool.name }}	0s
Integration: Workflow Compiler	40s
Integration: CLI Docker Build	1m 30s
Integration: Workflow Features	40s
Integration: CLI Compile & Poutine	43s
Integration: Parser Location & Validation	35s
Integration: CLI Progress Flag	1m 12s
Integration: CLI Completion & Other	52s
Integration: Workflow Rendering & Bundling	49s
Integration: CLI MCP Other	54s
Integration: Workflow Validation	44s
Integration: Workflow Tools & MCP	41s
Integration: CLI HTTP MCP Connect	1m 1s
Integration: Workflow Actions & Containers	43s
Integration: CLI Compile Workflows	47s
Integration: CLI Security Tools	54s
Integration: Parser Remote Fetch & Cache	38s
Integration: CLI Add & List Commands	45s
Integration: CLI Audit Logs & Firewall	41s
Integration: Workflow Infra	44s
Integration: CMD Tests	44s
Integration: Workflow Misc Part 2	44s
Integration: CLI Update Command	47s
Integration: CLI MCP Connectivity	1m 50s
js	2m 28s
js-integration-live-api	54s
canary_go	1m 18s
	39m 42s

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