Complete editor presentation capture from expected identities

[chubes4]

Summary

• query the independently complete editor-presentation identity contract before observing the canvas
• finish capture when the mature, still-current canvas contains every expected identity
• preserve fingerprint stabilization for editor targets without an expected identity contract
• cover a real browser canvas whose identity set keeps growing beyond the normal settle window

Closes #2425.

Verification

• npm run test:browser-routed-command-security
• npm run check (343 commands)
• git diff --check

Evidence

The regression reproduces the downstream timing shape: the canvas adds presentation markers every 100 ms, adds the final required marker after 4.1 seconds, and must emit complete expected/observed evidence within a 5-second command timeout.

AI Assistance

GPT-5.6 Sol via OpenCode analyzed the SSI promotion evidence, implemented the expected-identity completion condition and real-browser regression, and ran focused and repository-wide verification. I reviewed and orchestrated the work.