#1597 chore: Keep RPC boolean metadata validation strict

Summary

• Keep malformed boolean metadata from being treated as enabled flags across JSON-RPC request paths.
• Share the strict boolean reader used by envelope feature flags with compile request metadata parsing.

User Impact

• Requests that send strings such as "true" or "false" for boolean metadata continue to fail closed instead of changing request behavior.
• Boolean metadata handling is now less likely to drift between request paths.

Changes

• Added a shared strict JSON boolean metadata reader.
• Reused it for envelope feature flags and compile reload-wait metadata.
• Added focused EditMode tests for strict boolean parsing and case-sensitive/case-insensitive lookup behavior.

Verification

• dist/darwin-arm64/uloop clear-console --project-path "$(git rev-parse --show-toplevel)"
• dist/darwin-arm64/uloop compile --project-path "$(git rev-parse --show-toplevel)"
• dist/darwin-arm64/uloop run-tests --project-path "$(git rev-parse --show-toplevel)" --test-mode EditMode --filter-type regex --filter-value "(StrictJsonBooleanMetadataReaderTests|JsonRpcRequestProcessorCliVersionGateTests)"