chore: synchronize sta_timing_main with main

[yipeix]

Summary

• synchronize sta_timing_main with the latest main branch
• retain the iSTA RC waveform, SDF timing-check, and minimum-slew policy changes already merged through fix(iSTA): improve RC timing accuracy and add optional minimum slew policy #236
• incorporate the subsequent updates from main, including perf(iRT): optimize topology builder runtime #237

Current Status

This pull request currently introduces no additional source changes relative to main (0 changed files). The substantive iSTA timing improvements in this branch have already been reviewed and merged in #236.

Related Pull Requests

• fix(iSTA): improve RC timing accuracy and add optional minimum slew policy #236 - iSTA RC timing accuracy and optional minimum-slew policy
• perf(iRT): optimize topology builder runtime #237 - runtime performance improvements

Validation

• confirmed the pull request has no remaining file-level diff against main
• confirmed the branch includes the latest merged changes from main