fix(pixel): show temporary preview storage scope in final delivery

[Lightheartdevs]

A reading-list task claimed that preview inputs would survive reloads. Real browser testing found that Portal's embedded preview lost the inputs, while its direct published site preserved them across reloads and a fresh tab. The two viewing modes need distinct storage guidance.

Add a host-authored notice explaining that embedded-preview inputs may be lost and storage can differ in a separate tab. Keep it before the publication receipt so Portal retains it when rendering the preview card. Require verification at the exact URL before claiming persistence, retain guarded storage access and in-memory fallback, and leave sandbox isolation unchanged. This preserves model prose; it does not guarantee that the model will stop making contradictory claims.

Validation on candidate 3af52d7bfedc6fb14d5cbfd871d2c7bb5b425afc:

• Corrected production text passed 252 focused guide, prompt, publication and interaction checks without relaxing prompt-length limits.
• Clean Linux Pixel suite: 3,881 passed, 43 skipped. Real pinned OpenClaw 2026.6.33 runtime: four passed without skips. Portal publication rendering: eight passed.
• Live laptop diagnostic overlay: republished the existing reading-list snapshot unchanged, observed the corrected host notice, added/checked a book in each viewing mode, and verified embedded reload loses it while direct-site reload and a second tab retain it. Restored all 609 tracked baseline files afterward.
• Combined tree 9272b4c250baf1a1b4f1ab02d508c83868b42164 on current main c2060a4c passed 252 focused Pixel checks, 60 uninstall-volume tests and five tier-0 resolver checks.

All 75 exact-head CI checks passed before the guarded admin merge. Model prose can still make broader storage claims than its own checks establish; this change ensures that host guidance remains accurate and visible. Fresh final-main installs and full fleet qualification remain separate.