feat(rate): enforce cross-tab performance budgets

[d-sorgcodexagent]

Summary

• add a packaged, strict performance-budget manifest covering all nine React and nine PyQt visualization tabs
• enforce cold-open, resize-settle, stable-frame, post-settle movement, and browser CLS diagnostics in protected artifact probes
• move CPU-bound PyQt Plots computation behind a generation- and owner-bound killable subprocess with exact request/result authority and retained prior panes

Validation

• full web: 128 files / 1,070 tests
• focused Python authority: 70/70
• PyQt Plots async/GUI/render: 32/32
• PyQt all-tab DPI 1.0/1.5 performance/visibility: 1/1
• React three-viewport performance E2E: 1/1
• governance/assertion policy: 33/33; module-size and changed-test assertion gates green
• Python 3.12 / MyPy 1.13, Ruff/format, TypeScript, ESLint, production build, diff-check, and wheel resource inspection green

Scope limits

These are protected initial-production-state diagnostics, not arbitrary user-hardware qualification, result-workload qualification, approved visual goldens, persisted layout behavior, or formal assistive-technology evidence. Those remain open under #4433.