refactor(skill): switch eide rebuild to direct unify_builder runtime

[gaoguobin]

What

• replace the bridge-based path with a direct Python runtime package
• generate builder params from the current EIDE project model and run unify_builder directly
• auto-discover EIDE extension, tools, utils, toolchain, and use dotnet exec --roll-forward Major for unify_builder
• sync the runtime package into the skill bundle and remove the legacy bridge VSIX

Validation

• python -m unittest discover -s runtime/tests -p "test_*.py"
• real repo rebuild: BF_ECU_AppSwPrjtGen3_GD32F503_Y26M02
• real repo rebuild: BF_BootSwPrjtGen3_GD32F50x_Y26M02
• real repo rebuild: ECU_ARYV_FocSwPrjtGen2