Optimize parser hot paths

[himattm]

Summary

• Replace regex-based hint normalization in HintExtractor with direct string traversal.
• Replace SchemaParser hex color regex validation with fixed-length character validation.
• Add focused regression coverage for prefix stripping, separator normalization, ID rejection, and missing # hex colors.
• Stabilize the compose theme tests by waiting for async theme expansion instead of assuming fixed manual-clock timing.

This intentionally omits the generated .jules/bolt.md metadata from the duplicate generated performance PRs.

Supersedes #61, #62, #63, #64, #65, #66, #67, #68, #69, #70, #71, #72, and #73.

Validation

• ./gradlew -q --console=plain :halogen-core:allTests :halogen-engine:jvmTest :halogen-engine:wasmJsBrowserTest
• ./gradlew -q --console=plain apiCheck
• ./gradlew -q --console=plain :halogen-compose:jvmTest
• ./gradlew -q --console=plain :halogen-core:allTests :halogen-engine:jvmTest :halogen-compose:jvmTest :halogen-cache-room:jvmTest :halogen-provider-nano:testDebugUnitTest apiCheck
• git diff --check