Harden public README evidence status

[lishehao]

Summary

• Fix the stale CI badge URL from lishehao-ctrl/Auto-Load-off-Test to lishehao/auto-load-off-test.
• Add a conservative Evidence Status table distinguishing main evidence from draft PR Add capability discovery packaging sprint #6 and stacked draft PR Improve calibration and export workflow receipts #7.
• Add an Evidence Map linking architecture, operator guide, safety notes, no-hardware fixture/demo docs, deterministic demo data, and CI workflow.
• Re-state that current public validation is hardware-free and that live AWG/oscilloscope validation should not be claimed from this repository alone.

Public State Verified

• Public repo default branch is main on lishehao/auto-load-off-test.
• Public main README still had the old CI badge owner/repo before this change.
• PR Add capability discovery packaging sprint #6 is open/draft, targets main, and has public CI success on head commit 3f0f2bd.
• PR Improve calibration and export workflow receipts #7 is open/draft, stacked on PR Add capability discovery packaging sprint #6, and is not merged into main.

Validation

• git diff --check
• git diff HEAD~1 --check
• README local path check for linked docs, demo media, demo data README, and CI workflow
• rg -n "lishehao-ctrl|Auto-Load-off-Test/actions" README.md docs .github returned no matches after the fix

Honesty Boundary

• This PR does not add or claim live instrument validation.
• PR Add capability discovery packaging sprint #6/Improve calibration and export workflow receipts #7 remain draft work and are explicitly described as not merged into main.