⚡ Bolt: optimize filesystem reads by removing TOCTOU checks

[Tcode-Motion]

💡 What: Removed redundant Path::exists() checks that occurred immediately prior to std::fs::read and std::fs::read_to_string operations within techscript_cli.
🎯 Why: Calling .exists() before opening a file is a performance anti-pattern. It introduces a Time-of-Check to Time-of-Use (TOCTOU) race condition and doubles the required filesystem operations by mandating a stat syscall prior to every open/read.
📊 Impact: Eliminates redundant stat system calls in critical path loops such as configuration parsing, module cache checking, and workspace manifest resolution. This is expected to tangibly speed up incremental compilation, especially on environments with high file I/O latency (like certain CI or remote containers).
🔬 Measurement: Verify by running strace -c -e statx,openat tsc run ... and observing a significant reduction in statx calls. Ensure CLI still handles missing configs gracefully.

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PR created automatically by Jules for task 13392758860696189895 started by @Tcode-Motion

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