⚡ Bolt: optimize formatted string concatenations with write! macro

[Tcode-Motion]

💡 What: Replaced instances of .push_str(&format!(...)) with direct write!(..., ...) macro calls via std::fmt::Write across several modules (CLI, diagnostics, profiler, runtime builtins, and VM debugger).
🎯 Why: Using format! inside a loop creates temporary String allocations that are immediately appended and discarded. This puts unnecessary pressure on the allocator. Using write! directly to a pre-allocated String buffer (or an existing formatter) completely eliminates these intermediate allocations. This was previously identified as a bottleneck in string rendering contexts.
📊 Impact: Reduces memory allocations inside diagnostic rendering, profiler string generation, VM trace outputs, and AST/IR disassembly loops. Expected faster output formatting operations with lower peak memory footprint.
🔬 Measurement: Verified correctness using cargo test --workspace tests. No regressions in functionality, with potentially faster string builder execution times.

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PR created automatically by Jules for task 8436430878582263470 started by @Tcode-Motion

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