Error toast redesign: dedupe repeats and anchor above the station menu

[rodrigohpalmeirim]

Summary

Error toasts had two problems: they were anchored bottom-center, right on top of the station menu's bike list, and repeated messages (e.g. from retried requests) stacked up as duplicates, eating screen space.

Dedupe with counter

Re-adding a message that's already visible now refreshes its timer and bumps a ×N badge on the existing toast instead of stacking a duplicate (ui.svelte.ts).

New look and placement

Toasts keep the warning-orange palette but get the rounded card shape with a warning icon, and anchor just above the station sheet's top edge instead of the screen bottom, so they never cover the bike list or its unlock buttons.

Before	After

Anchor tracking

The sheet reports a new anchorTop binding: its predicted top edge, computed from the skeleton list height (known from the station's bike count the moment a station is tapped) rather than a rect measurement, so it's correct while bike info is still loading and while the resize animation is in flight. The toast container transitions bottom over 300ms, so anchor changes glide instead of snapping. While dragging, the last anchor is held; during trips and with no sheet open, toasts fall back to the bottom, which is free then.

The existing posTop binding (used by the location button, which intentionally hides while the sheet loads) is unchanged.

Dev tooling

giraDebug console hooks (dev builds only): fakeLogin(), fakeStations(), selectStation(), and addError() allow exercising the map UI and toasts without a real account.

Testing

• svelte-check: 0 errors, 0 warnings; eslint clean on changed files; 45/45 vitest tests pass.
• Verified visually with Playwright in light and dark mode, including a station-switch sequence with an artificially delayed bikes fetch: the toast holds/moves to the predicted anchor mid-load and glides to the settled position when data arrives.