Android: skeuomorphic 1:1 desktop chrome + edge-snap panel + smooth motion

[devin-ai-integration]

Summary

Fix three high-signal issues reported in PR #17's APK test (Android only — no desktop code touched):

1. Dark "fleck" at the panel's rounded corners. The previous panel was vertically centered and rounded on all four corners, so the rounded top-right / bottom-right corners exposed the dim scrim through the rounding, and there was a horizontal strip of scrim above / below the panel. The panel is now:

   • Full-height (Gravity.END | Gravity.TOP, MATCH_PARENT height), so no scrim strip is visible.
   • Asymmetric cornerRadii — only the inner edge corners are rounded (top-left + bottom-left for right dock, mirrored for left). The outer corners are square and sit flush against the screen edge, so the rounding is never visible against the scrim. Same recipe as the desktop's border-radius: var(--panel-radius) 0 0 var(--panel-radius).
   • Scrim opacity reduced from 50% to 31% so the home screen behind the panel reads softer.

2. Open / close not smooth. The panel now slides with PathInterpolator(0.2, 0.8, 0.2, 1) (identical to the desktop's cubic-bezier(0.2, 0.8, 0.2, 1)). The view tree is laid out before the animation starts (so the first frame isn't the cost of inflating 70+ children), hardware layers are forced for the duration of the slide, and a minimum motion duration of 180 ms is enforced. The close transition uses a matching cubic-bezier(0.55, 0, 0.7, 0.3) ease-in.

3. Edge handle (bubble) looked cheap. Redrawn with a proper skeuomorphic stack:

   • Hardware soft shadow via View.elevation + ViewOutlineProvider.
   • Additional canvas shadow layer (matches desktop box-shadow: -8px 16px 28px rgba(15,23,42,0.08)).
   • 2-stop body gradient from the per-theme --handle-bg token (already in R.color.handle_grad_top/bot).
   • 1dp inset top highlight (inset 0 1px 0 rgba(255,255,255,0.72)).
   • Lucide PanelRightOpen glyph (panel outline + rail + chevron) instead of the bare 3-stroke icon.

Plus a full skeuomorphic chrome system in Drawables.kt:

• New panelSurface(..., dockEdge, radiusDp) returns a LayerDrawable with body gradient (top-tinted) + transparent inset top highlight, with asymmetric cornerRadii for the dock edge.
• New chromeButton, railButton, captureRow factories return LayerDrawable(body-gradient, top-highlight) with a 1dp border. Pressed / active states swap colors and pick up the accent line border, matching .sidebar-rail button.is-active.
• taskRow now also uses the gradient + highlight + border layered drawable instead of a flat fill.
• primaryButton produces an accent-gradient body for the capture-row + button with a faint top highlight, matching .add-task in the desktop CSS.

Testing

• ./gradlew assembleDebug (Android module)
• ./gradlew assembleRelease (signed)
• ./gradlew lint
• npm run build — not relevant, no desktop changes
• npm run lint — not relevant, no desktop changes
• cargo check --manifest-path src-tauri/Cargo.toml — not relevant, no Rust changes

Platform Notes

• Android: All changes scoped to /android/. Phone test required (overlays don't run in CI emulators). The fixes are functional (gravity, drawable layout, motion curve) so they don't require device-specific validation, but visual polish should be confirmed on real hardware.
• Windows / macOS: no changes.

Screenshots

Visual changes are panel-shape, animation curve, and elevation — all of which need a phone to verify. APK is built by the existing android.yml workflow and uploaded as both a workflow artifact and a rolling android-latest prerelease once this merges.

Link to Devin session: https://app.devin.ai/sessions/a29437e8dd5a412393c371c333455c2a
Requested by: @Leonxlnx

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