[sandesh-sp]

Closes #576.

Summary

• Map camera on the bus. map:getViewState now includes bearing and pitch. deck.gl reads both from its camera. Leaflet always reports pitch 0 and reports the bearing its projection gives at the map centre, so polar maps show where north is.
• map:resetNorth. On a rotated deck.gl view, it eases back to north and keeps the tilt. On a view that already faces north, it flattens the tilt. Leaflet can't rotate, so it returns false and leaves the view alone.
• Compass button in Map Control. The button sits right after the zoom buttons, behind a Compass checkbox (showCompass) that is on by default. The needle turns against the bearing and tips with the pitch. It updates on map:moveend, and during map:move it reads the camera at most once per animation frame. Hovering shows the bearing and tilt, and clicking resets the view toward north.
• Styling. The needle uses the bar's icon color through its rest, hover and active states. The south half is faded so north stands out. The glyph is drawn at 20px; the bar's other glyphs are 16px.

Test plan

• npx vitest run: 211 files, 3,610 tests pass
• deck.gl: rotate and tilt the map, and the needle follows the camera smoothly
• Hover the compass to see the bearing and tilt; click it to ease back to north with the tilt kept, then click again to flatten
• Unchecking Compass in the Map Control config removes the button
• Leaflet: the compass shows north-up, and clicking it does nothing
• The compass matches the other bar icons at rest, on hover and when active