feat: hub-based architecture for automatic shade discovery

[safepay]

What is this?

This PR takes a different approach to managing PowerView BLE shades. Instead of setting up each shade individually as its own config entry, this introduces a hub-based model where a single config entry represents your PowerView home and shades are discovered automatically via BLE.

This includes all the work from #25 and #28 which I have closed (but left the branches).

What this PR changes (hub-based)

You set up the integration once — point it at your hub (or enter the key manually) — and shades are automatically picked up as they're discovered over BLE. New shades appear without any additional config. Shade names are pulled from the hub so they match what you already see in the PowerView app.

The main changes:

• __init__.py — manages a collection of coordinators (one per shade), registers a BLE callback to pick up new shades, and fetches friendly names from the hub API
• config_flow.py — simplified to a single setup step: choose how to provide the home key (fetch from hub, enter manually, or skip)
• Entity platforms — use a dispatcher pattern so entities are created for both existing and newly-discovered shades
• Velocity — adds velocity control for shades that support it via number.py
• Shade Capability Detection — adds detection for all shade types
• Top Down Shades — adds support for Top Down Shade types
• Addresses Add type 54 vertical blinds support (position + tilt) + fix battery_charging bug & possible guide for adding other shade types included #27
• Fixes the bit addressing that PR Feature/type 8 #16 was trying to fix without breaking other shades
• Tilt on Closed Shades — adds support for Tilt on Closed Shade types

Why I think this is the better path

• Zero-touch — add a shade to your home and it shows up in HA on its own
• One config entry instead of one per shade
• Names stay in sync with the PowerView app
• Simpler setup — no multi-step shade picker, just provide the key and go
• Scales naturally — 3 shades or 30 shades, same amount of setup

Closes #3
Closes #8
Closes #21
Closes #27

[safepay]

Sorry about the monster PR, but this brings the integration in line with modern HA architecture and should work with most blinds except the ones that have multiple blinds.

Thanks for a great integration. My setup is working perfectly. But I don't own all the blinds so I can't test everything.

At least it has the necessary information to move to the next step regarding dual and triple blind support, but that requires a bit of a refactor.