Model probes report reachability and authentication

[ousamabenyounes]

Summary

• Describe successful chat and embedding probes as establishing reachability and authentication.
• Keep the returned reply and embedding dimension so the result still shows what the probe observed.
• Apply the same honest wording in English and Chinese.

Closes #528.

Test verification (RED → GREEN)

On unmodified dev, the new copy contract failed because the result was only Connected (OK):

Expected: "Reachable and authenticated (OK)"
Received: "Connected (OK)"

After the patch, all 9 web tests pass. Temporarily restoring the old formatter reproduces the same RED failure.

Validation

• Changed executable production lines: 100% directly invoked and asserted (4/4).
• Full local suite: migrations twice, formatting, workspace clippy with warnings denied, 668 Rust tests passed / 0 failed / 1 ignored, required DB-backed store tests, workspace build, 9 web tests, and the web production build all passed.
• Two independent Codex reviews, including the resolved OCR rule set, accepted the final diff.

[WaylandYang]

Merged. This is the wording #528 asked for: a passing probe now says what it tested, in both languages.

Two things changed on your branch before the merge, pushed as a commit of their own so the history shows who did what. The Chinese result now reads 已连通，认证通过, the same statement in two clauses. And settingsProbeCopy.test.ts is gone: a test that asserts an i18n string equals itself covers no behaviour and doubles the places a copy change has to touch, so this repository keeps copy free of tests. Thanks for the fix.