feat: floating popover editor for sites, links, and simulations (#804)

[wilhel1812]

Summary

• Replaces resourceDetailsPopup and linkModal ModalOverlay editors with MapEditorPanel — a floating popover anchored to the invoking sidebar button
• Unifies edit + create into a single panel for sites, links, and simulation presets (including AccessSettingsEditor and all existing fields)
• Dismissed by ESC, click outside, or × button; mobile renders as a bottom-sheet
• Position is computed with right-of-trigger preference and full viewport collision clamping (16 px margin)
• mapEditor slice added to appStore (openMapEditor / closeMapEditor); trigger buttons pass getBoundingClientRect() at click time — no ref threading required
• useMapEditorFormState hook owns all draft state previously spread across Sidebar.tsx

Test plan

• Click a site pencil → popover floats to the right of the pencil, fully visible in viewport
• Click "Add Site" → same panel in create mode, lat/lon pre-filled from map center
• Edit site name → Save → sidebar reflects change, popover closes
• Press ESC → popover closes without saving
• Click outside popover → closes without saving
• Click × → closes without saving
• Click link pencil → link editor anchored to that row's pencil
• Click "Add Link" → link panel in create mode
• Simulation "Edit" → simulation editor popover (name / description / access)
• Mobile (<768 px): all three editors appear as bottom sheet with slide-up animation
• Resize browser while popover is open → panel stays visible (recomputes position)
• npm test — 461 tests pass; npm run build — clean

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