added custom background image with path and other overlay support

[hansherlighed]

Overview

This PR adds two major features to the Roborock Custom Map integration and lovelace-xiaomi-vacuum-map-card:

PR for RoborockCustomMap needed for this to work Lash-L/RoborockCustomMap#38

1. Static background image support in the card: overlay a custom floor plan image (architectural drawing, manual map, etc.) underneath the live vacuum map, with calibration-based alignment
2. Configurable map rendering in the integration: select which overlays to show (path, charger, obstacles, etc.), hide floor/walls/rooms for transparent rendering, and rotate the map if needed

These work together to enable transparent vacuum overlays on top of static floor plans, replacing the official map with a custom rendering.

What's New

lovelace-xiaomi-vacuum-map-card Changes

• New map_source fields:
  • background_image (string): URL of a static image to display underneath the map
  • map_image_opacity (0.0–1.0): fade out the live map to reveal the background
  • background_image_calibration (1–3 point pairs): align the background to vacuum coordinates via affine/similarity/translation transforms
• Added computeBackgroundMatrix() function for 1/2/3-point calibration
• Background image rendered at z-index: -1, map overlays rendered on top

RoborockCustomMap Integration Changes

• New options UI (settings → devices → Roborock Custom Map):

  • Per-drawable toggles: charger, path, cleaned area, obstacles, zones, walls, etc.
  • show_background, show_walls, show_rooms: control map layers
  • show_floor: hide MAP_INSIDE/MAP_SCAN/CARPETS/removed-area pixels (light green zones)
  • Per-map rotation select entity (0°, 90°, 180°, 270°) — rotates both image and calibration

• Transparent rendering: with all backgrounds disabled + show_floor=False, the rendered image contains only path, charger, and vacuum position on a transparent background

• Floor color stripping (_remove_floor_colors()): PIL post-processing that makes all floor-colored pixels fully transparent (alpha=0)

• Map rotation support: rotation stored in hass.data, applied to both the image and calibration point coordinates so overlays stay aligned

• Race condition fix: _custom_cached_map is only written once after all processing (rendering + floor stripping + rotation), preventing concurrent requests from returning partially-processed images

Why This Approach

Frontend calibration (card) vs. backend rendering (integration)

• The card handles the background_image_calibration (1–3 points mapping background pixels to vacuum coordinates)
• The integration handles drawable selection and image transformations (rendering, floor stripping, rotation)
• This separation allows users to:
  • Use the custom card with any custom integration (not just this one)
  • Use the integration's transparent rendering with other cards
  • Combine them for the best of both worlds

Why rotation in the backend, not CSS

• Frontend rotation (card-mod) rotates only pixels, leaving calibration unchanged → overlays misalign after rotation
• Backend rotation rotates both image and calibration map coordinates → overlays and interactions stay correct
• Persistent: Select entity with RestoreEntity saves orientation across restarts
• Live: no reload needed; dispatcher signal triggers immediate cache bust

Why transparent rendering instead of cropping

• With show_floor=False, the custom extractor removes floor colors post-processing, leaving only important overlays
• PIL is already a dependency (for rotation), so no new deps added
• Post-processing is fast (single pass over pixel data in executor)

Technical Details

File changes:

lovelace-xiaomi-vacuum-map-card changes:

• src/types/types.ts: Added BackgroundImageCalibrationPoint interface; added map_source fields
• src/xiaomi-vacuum-map-card.ts: Added computeBackgroundMatrix(); render <img id="background-image">; apply CSS matrix transform; wire up _updateBackgroundImageTransform()

Backwards Compatibility

• Custom integration: Default behavior unchanged (no custom options → render default map)
• Rotation defaults to 0° (no rotation)
• Existing users unaffected unless they explicitly enable options
• Card: background_image is optional; if not set, card behaves as before

Tested With

• Xiaomi Vacuum Map Card (lovelace)
• Roborock S7 MaxV (multiple maps)
• Multiple floor plans with different aspect ratios
• Calibration with 1, 2, and 3 points
• Map rotation (0°, 90°, 180°, 270°)
• Drawable toggles and room/zone interactions
• Transparent rendering + static background overlay