Add possibility to per-map override a Custom Floor Plan

[java-devil]

Hey follow-up to: #16

There are two alternative solutions to the same problem currently "hanging".

However, based on my personal experience I believe a more user-friendly approach is required. Especially one that is resilient to the map inevitably drifting with time. One which allows the User to manually self-correct at any moment. Preferably from the UI. While supporting multiple floors.

Given HAs limitations - this is the most comprehensive flow that I was able to come up with (safe for something crazy to maintain like a full-blown JS custom card):

1. `Settings` → `Devices & Services` → `Roborock Custom Map` → press `Configure`.
2. Pick a Floor (only if > 1 available).
3. Choose your Floor Plan (PNG, JPEG or WebP); a Live Preview appears as you do so.
4. Press `Submit` — the Floor Plan applies immediately as-is, with no adjustments.
5. On the next view, optionally adjust the horizontal/vertical offset/scale
   of the Custom Floor Plan, or the relative rotation of the Physical Walls.
   The Physical Walls are imposed over the Custom Floor Plan for your convenience.
   The Live Preview refreshes in near-real-time.
6. Press `Submit` once more — to keep the adjustments,
   or simply press `X` — to keep the Floor Plan as-is.

Upload Screen

Adjustment Screen

Removal Screen

Full Disclosure

I am no "Pythonista". Nor am I very aware of the idioms of HAs development. I leaned on an LLM quite a bit during development, and it did end up replacing in the end quite a bit of my initial draft. Having said that. I AM a professional SE. I did know what to prompt, what to check, and did so meticulously. This entire effort took a few solid days over many iterations / bugfixes.

Cheers,
Adam

[java-devil]

@Lash-L some weird shenanigans seem to be happening on your repositories. This PR seems to have somehow fallen in the cracks, and it doesn't display on the open PR list. There is in fact only one PR there, despite the number next to PRs still claming otheriwse.

Please confirm that you still have visibility into this issue, and that I don't have to reopen it. There is no urgency to you reviewing the code. I just need a quick "I see you, I'll get to this eventually" ;)

[Lash-L]

Haha I knew this PR existed! Was confused when I didn't see it.

My account was false flagged banned. I got my account back but there's some weirdness. I see it!