improvement: type-specific governance size thresholds

[tbitcs]

Summary

Scale governance file size thresholds based on project type. FPGA/embedded
projects inherently have more rules than web apps.

Proposed Approach

Add optional threshold overrides to scaffold.yml:
governance_thresholds:
rules: 1000
workflow: 500

Or auto-scale by type:

• fpga-rtl, yocto-bsp, embedded-hardware: rules=1000, workflow=500, verification=600
• cli-python, library-python: rules=400, workflow=300
• Default: current values

Related

Current static thresholds were raised globally but could be smarter per type.

[tbitcs]

Implemented in 279eec7