Prepare 1.8.0 release and one-time highlights

[Muawiya-contact]

Prepare version 1.8.0 with its required one-time What's New card. The card describes six benefits from the merged work: offline saved lessons/examples, automatic synchronization, offline topic choices, lighter startup and older Saved search/filter access, password visibility, and refreshed account emails.

Changes:

• Set the app version to 1.8.0 and preserve native runtime 1.3.0 for this JavaScript-only mobile release.
• Scroll longer highlight lists while keeping the heading and dismissal controls visible on smaller screens.
• Add browser coverage for the current version, six viewport/theme combinations, and dismissal across offline restart.
• Record release validation and the remaining production migration prerequisite.

Validation:

• 145 backend tests passed, no skips, with disposable PostgreSQL 16 and dummy Auth configuration.
• 33 Node 24 tests and TypeScript passed.
• Android and web production exports passed with dummy public configuration.
• Release-card browser regression passed at 320×568, 390×844, and 844×390 in both themes; screenshots inspected.
• Documentation paths and whitespace checks passed.

This preparation PR targets develop and preserves the focused commits. A read-only production check confirmed migration 0010 is missing. Applying it needs explicit owner authorization following automatic approval review; no production write was performed and the migration ledger is unchanged. Per RELEASING.md, apply and verify it before opening develop → main.

The generation-budget deployment also needs the documented shared cap and first-day rollout handling. Draft #187 remains deferred. Physical-device accessibility and actual email delivery remain unverified. This PR does not merge production.