⚡ Bolt: [performance improvement] Cache regex in HintExtractor

[himattm]

💡 What: The optimization implemented was hoisting Regex("""\s+""") to a private val property WHITESPACE in HintExtractor.kt.
🎯 Why: Creating a Regex instance dynamically within a function call compiles the pattern every time, which generates unnecessary CPU overhead and garbage collection in hot paths.
📊 Impact: Eliminates regex compilation cost per extract invocation, saving memory and decreasing execution time.
🔬 Measurement: Verify the static property definition and test regressions via ./gradlew :halogen-engine:test.

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PR created automatically by Jules for task 8655993748519976895 started by @himattm

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