fix: updates in diagnosis report + submit report button

[Imod7]

Description

• The diagnosis summary (at the top) only showed the total of pass/fail and the total of skipped methods were not mentioned.
• The "Submit report" button put the whole report in the URL, which failed (in Chrome) with "URL too long".
• Also fixes a broken example payload that made one signing method fail to load on a phone.

Changes

• playground/src/lib/auto-test.ts - skipped methods now carry a short reason ("service not yet wired up by hosts" / "host surface intentionally deferred") so the Details column isn't empty.
• playground/src/components/DiagnosisView.tsx - the on-screen summary now shows a skipped count. "Submit report" copies the full report to the clipboard and puts a smaller version (success details dropped) in the issue URL.
• playground/src/lib/diagnosis-report.ts - the report gets a N success · N failed · N skipped summary line and now lists skipped rows. Adds a compact mode (drops success details) and a URL-length cap: if the report is still too big, the issue opens with a "paste from clipboard" note instead of failing.
• rust/crates/truapi/src/api/signing.rs - fixes the sign_payload_with_legacy_account example, which used an incomplete call payload the phone couldn't decode ("fails to load"). Now uses the same valid payload as sign_payload.
• playground/CLAUDE.md - updates the file descriptions to match the above.

Notes

• The compatibility matrix is unaffected: it ignores skipped (⏭) cells and only reads pass/fail.
• The full report is always on the clipboard, so nothing is lost when the URL falls back to the paste note.

[valentinfernandez1]

Let's not change the current diagnosis view behavior, skipped methods should show as failed and the reason why they were skipped but let's not remove them from the matrix