feat(web): add account appearance preferences

[JacobWeyer]

Problem

The app has fixed colors and fonts. Its browser-wide theme mode does not follow an account to another device. Accounts in one browser can also share that mode.

Closes #1593.

Fix

• Store a validated appearance document per account through authenticated GET/PATCH routes. Use atomic revision checks, a per-account cache, retained drafts, retry, and explicit conflict choices. Offer an explicit import for old browser settings.

• Add Appearance controls for custom schemes, JSON color import/export, and independent body, heading, and code fonts. Add Dracula, Catppuccin, Nord, Solarized, and Gruvbox for light, dark, and system modes. Keep current defaults.

• Apply palette and font roles across previews, code, diffs, editors, and terminals. Serve optional Inter and Fira Code fonts from local Fontsource assets with full license notices. Preserve reference ANSI colors and readable terminal selections.

• Add migration 0095, shared package inputs for both images, CI path coverage, design documentation, and function docstrings. ADR 0124 records account persistence and revision rules.

• Derive font options from shared IDs with compile-time metadata checks. Resolve unknown IDs to role defaults in application styles, previews, heading width, and terminal font measurement.

Ghostty 0.4.0 retains colors in existing terminal text cells. Its public API updates the background, cursor, selection, and font without a reconnect.

Test

Current font-registry correction:

• Web format check, lint, production build, and 66 focused appearance/provider/terminal/UI tests passed.
• Both browser suites passed under production CSP, including local font loading, fallbacks, account saving, and reload.
• Orchestrator typecheck and 16 shared-contract/API tests passed.
• Temporary compiler checks confirmed that missing font metadata fails with TS2741 and extra metadata fails with TS2353.
• Registry tests cover all accepted IDs, unchanged defaults and UI order, supported font stacks, unknown-ID fallbacks, heading width, and terminal load-before-measurement. git diff --check passed.

The initial feature validation passed all 1,046 web tests and 20 contract/API/live-Postgres/migration-journal tests. A fresh Postgres 18 database accepted all migrations; a repeat run made no changes. The font correction does not change migrations or accepted API IDs.

Workflow YAML and shared-package path selection passed during feature validation. Actionlint had no new findings compared with the base branch. No local Rust checks were needed for the web and shared TypeScript changes. Current-head CI Gate and the contributor CLA check must pass before merge.

[engrams-agent]

✅ engrams reviewed b798638: no findings.

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[JacobWeyer]

I have read the CLA Document and I hereby sign the CLA

[engrams-agent]

Engrams review

Verdict: 1 finding posted inline.
Severity: Critical 0 · High 0 · Medium 1 · Low 0
Categories: 📐 Maintainability & Code Quality: 1

View the full engrams review

[engrams-agent]

Engrams review

Verdict: 1 finding posted inline.
Severity: Critical 1 · High 0 · Medium 0 · Low 0
Categories: 🎯 Functional Correctness: 1

View the full engrams review