feat: system widgets foundation + price widget

[jvsena42]

This PR:

1. Adds a Bitcoin Price home screen widget using Jetpack Glance
2. Implements independent widget preferences stored in a separate DataStore
3. Uses WorkManager for periodic background data refresh (15-minute intervals)
4. Includes a configuration Activity for widget settings on click
5. Renders a sparkline chart via Bitmap using Android Canvas API

Description

Introduces the foundation for Android home screen widgets (AppWidgets) using Jetpack Glance, starting with the Price widget. The widget displays enabled trading pairs with price, change percentage, and a line chart — matching the in-app Price widget layout.

The architecture reuses the existing PriceService for data fetching (via a new fetchData(period) overload) while keeping widget preferences completely independent from the in-app widget system through a dedicated AppWidgetPreferencesStore backed by its own DataStore file.

A Glance design system (GlanceTextStyles, GlanceColors) ports the app's typography and color tokens to Glance equivalents, and shared components (GlanceWidgetScaffold, GlanceDataRow) provide consistent widget layouts.

Preview

Screen_recording_20260421_153032.webm

QA Notes

1. Long-press the home screen and select "Widgets"
   • Find "Bitcoin Price" in the widget picker
   • Verify the preview shows a price layout with mock data
2. Add the widget to the home screen
   • Verify the configuration screen opens with trading pair and period options
   • Toggle pairs and period, tap Save
   • Verify the widget updates to show selected pairs with price, change %, and sparkline chart
3. Wait 15+ minutes or force-stop and reopen
   • Verify the widget refreshes data via WorkManager
4. Tap the widget
   • Verify it opens the widget settings screen
   • Verify the widget update after saving new preferences
5. Long-press the widget
   • Verify the widget is resizable
   • Verify the chat is hidden if not enough vertical space
6. Verify the OS widget settings are independent from internal app widgets

[pwltr]

I tested on device, works as described, except it did not seem to update price for me automatically (waited ~30minutes). Only after I tapped the widget did it reload. Still don't know anything about Kotlin so won't review code.

EDIT: have seen it update now

[claude]

Code review

Found 2 issues: 1 CLAUDE.md violation and 1 bug.

[piotr-iohk]

I've approved all individual stacked PRs. I think it looks good functionally. Also e2e tests updated to cover in app redesigned widgets.

There are some outstanding items that I think would be good to address before releasing this feature:

• behavior described here: feat: headlines widget v61 + OS widget #919 (comment) (seems to concern all OS widgets)
• if possible consider ordering suggestion of OS widgets on add screen (IMHO price, blocks, weather could be on top if possible)
• in app small widget support... either support it in app view or remove small preview for now. Otherwise it may be a bit confusing as why only wide version is supported despite saving the small one.

[ovitrif]

Code LGTM 🎉

Going to test tomorrow.

[ovitrif]

nit: according to AI, it’s safe to always use ImmutableList, also in business logic. Doing so would remove the need to convert for Compose UI stability.

[jvsena42]

I'll create a branch on top of the stacked with all the fixes, to reduce the work with conflicts