fix: render terminal final column

[almogdepaz]

Summary

• stop Ghostty-web's in-canvas scrollbar from painting over the terminal's final 14 pixels
• initialize the desktop sidebar in its persisted-safe collapsed geometry
• add a real-canvas pixel regression for final-column rendering and final-width layout_stable
• regenerate the bundled and embedded browser assets

Root cause

Ghostty-web 0.4.0 allocates the full canvas width to PTY cells, then renderScrollbar() paints a 14px background strip over that same canvas after text rendering. Buffer and geometry diagnostics therefore reported all columns correctly while the final cells had no visible pixels.

Verification

• bun test: 1,831 passed
• full Playwright suite: 110 passed, 124 expected project skips
• focused desktop repeat gate: 10/10 passed
• desktop, iPhone SE, and iPhone 14 pixel regression: passed
• clean-install Bun patch application: passed for ESM and UMD distributions
• TypeScript checks and git diff --check: passed
• live server-only deploy: final-cell ink 34, reference-cell ink 34; 159/159 columns visible
• broker PID unchanged and all 6 pre-existing sessions preserved

Behavior retained

Wheel, touch, and terminal scrollback behavior remain intact. The destructive in-canvas visual scrollbar is removed because there is no reserved canvas gutter for it.