⚡ Bolt: [performance improvement] Eliminate unnecessary Vector allocations in string processing

[cloudesize67-cmd]

💡 What:

Replaced .collect::<Vec<_>>().join("") with .collect::<String>() in xdk-lib/src/casing.rs. In xdk-build/src/python.rs, eliminated intermediate vector allocations by using .split('\n') and .split(' ') along with iterator pattern matching.

🎯 Why:

To reduce unnecessary heap allocations (creating vectors solely for intermediate operations) in standard SDK string manipulations, which marginally increases heap utilization and hurts instruction cache layout on large text loads.

📊 Impact:

Slight improvement in performance and memory utilization during case generation and terminal output logging.

🔬 Measurement:

Run make test-generator and make check to verify output consistency and that no regressions are introduced. The standard tests will confirm no structural outputs differ.

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PR created automatically by Jules for task 1643288645536228947 started by @cloudesize67-cmd

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