#434 Epic: Theme store and Appearance redesign

[Anonymous]

Originally created by: kristofferR

Tracking issue for downloadable themes and the Appearance tab redesign.

Themes come from a catalog instead of shipping inside the app. The app keeps only the small palette themes (Default, OLED Black, Graphite, Warm). The catalog starts with ten ports from fMess and its forks (WhatsApp, Teams, Google Chat, Slack, GitHub, GitHub Split, Terminal ×4), with their fake app chrome and brand art removed, running on Chatpane's own page hooks. The Appearance tab is redesigned around them.

Plans and mocks

• Theme store: https://plans.kristofferr.com/d/w5svpa5g4twy (chosen: layout C, every theme in one gallery, click to use, expand on hover)
• Appearance tab: https://plans.kristofferr.com/d/sg4cwqvputno (chosen: layout B with app icon selector 1)

Sub-issues, in rough order:

• [x] [#422] Appearance tab: grouped cards layout
• [x] [#423] App icon: pick the icon for light and dark mode directly
• [ ] [#424] Theme hooks: element marks for layout themes
• [ ] [#425] Theme hooks: per-message sender, time and run marks
• [ ] [#426] Theme catalog: a themes/ folder in this repo
• [ ] [#427] Theme store: download, verify and update catalog themes
• [ ] [#428] Theme gallery: every theme one click away, with a bigger preview
• [ ] [#429] Port the WhatsApp, Teams and Google Chat themes
• [ ] [#430] Port the GitHub and GitHub Split themes
• [ ] [#431] Port the Terminal themes
• [ ] [#432] Port the Slack theme
• [ ] [#436] Chat check: every theme across chat kinds, chat themes and light/dark
• [ ] [#433] Theme authoring guide and chatpane-theme agent skill

[#422] and [#423] stand alone. [#424] → [#426] → [#427] → [#428] is the store's spine; the ports need [#424] (and [#425] for Terminal and Slack) and land in themes/ (#426). [#436] gates each port.

Decisions: the catalog is a top-level themes/ folder in this repo, fetched from raw.githubusercontent.com (decided). Plan defaults, not yet confirmed separately: HTTPS from one host plus SHA-256 per file, no index signing; catalog themes update automatically; screenshot previews from a demo account.

Open questions

• Google Chat, Slack, GitHub and Terminal come from unmerged work (toanbku/fmess#50, darkpiv's fork, lyng148's PR). All MIT; ask the authors before publishing?
• Theme names: keep "WhatsApp", "Teams", "Slack", "GitHub", "Google Chat" (logos removed), or say "… style"?

Ref [#357], Ref [#369], Ref [#349]