feat(ui): Redesign the apps hub and settings pages and polish details

[timlangner]

Brings the egui app in line with the "Guided Stepper" design handoff and fixes a batch of fidelity issues found during review. Re-applied onto the rebuilt main and reconciled with the recent amend (kept the token-value redaction, the View your stash action, the Minimize to tray rename, and the reworded sync copy).

Title bar

• Remove the hide-to-tray window button (keep minimize / maximize / close).
• Status pill: leading status dot, controlled compact size with roomier padding, ink-centered dot + label.

Hub

• Icon tile and <PHASE> · STEP n OF 4 eyebrow on one row.
• Light gold radial top glow, clipped to the body (no bleed over the title bar / rounded corners).
• Hero content vertically centered (measured) so the Synced screen no longer overlaps the footer.
• Busy states show a labelled spinner row instead of a bare spinner.
• Full-height rail/hero divider; proper cog for the settings glyph.

Footer

• Gear + "Settings" ghost button (real cog), centered in the button.
• Emphasized synced account name; icons ink-centered with their text.

Settings

• ← Settings header; full-width scroll so the bar hugs the window edge; drag-to-scroll disabled.
• Activity log folded into Troubleshooting as an inset panel.
• "What does Sync do?" link, full-width Quit, inline network row with an aligned Refresh button, "Match Windows" language label, adapter names without the GUID.

Modals

• Shared padded, dimmed-backdrop modal; explainer gets an accent badge.

Theme / widgets

• Softer pressed (active) state so controls stay readable on click.
• Pointer cursor on all buttons/dropdowns; pill + combo width tokens.

main.rs enables the borderless/transparent/resizable window the custom chrome relies on.

Verification

• cargo build clean, cargo fmt --check clean, cargo test → 55 passed.