Port BluetoothLEHelper from 7.x

**Source**: Microsoft.Toolkit.Uwp.Connectivity (7.x)
**Destination**: CommunityToolkit.WinUI.Helpers (8.x) — not yet ported

## Description

The BluetoothLEHelper class provides functionality to easily enumerate, connect to and interact with Bluetooth LE Peripherals.

## Prerequisites

None identified.

## Porting Basics

- [ ] Namespace updated to `CommunityToolkit.WinUI.*`
- [ ] Code for UWP, WinUI3 and Uno Platform consolidated
- [ ] Desired MultiTargets configured
- [ ] Sample code migrated
- [ ] Concept docs migrated
- [ ] Tests migrated and passing

## Quality Evaluation

See [Porting Criteria](https://github.com/CommunityToolkit/Windows/wiki/Component-Quality-Evaluation) for detailed evaluation guidance.

- [n/a] UX: Accessibility reviewed
- [n/a] UX: Visual design reviewed
- [n/a] UX: Interaction patterns appropriate
- [ ] DX: API surface reviewed
- [ ] DX: API flexibility appropriate
- [ ] DX: Documentation updated
- [ ] MX: Breaking changes documented
- [ ] MX: Domain isolation appropriate
- [ ] MX: Test coverage adequate

## Tracking Gaps

*No gaps identified — porting work not yet started.*

## Closing

- [ ] All Porting Basics complete
- [ ] Quality Evaluation reviewed
- [ ] Gaps filed as sub-issues

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## 7x Documentation Inventory

**Docs ported to 8x**: n/a

**Docs not in 8x**:
- Summary
- BluetoothLEHelper class
- Properties
- Methods
- Events
- ObservableBluetoothLEDevice class
- Properties
- Methods
- ObservableGattDeviceService
- Properties
- ObservableGattCharacteristics
- Properties
- Methods
- Example

## 7x Source Inventory

**Source already ported to 8x**: n/a

**Source not ported to 8x**: n/a

## Notes

- Not currently planned for porting. Open to community interest.
- **Archive redirect**: https://learn.microsoft.com/en-us/dotnet/communitytoolkit/windows/archive/bluetoothlehelper

Start with the archived BluetoothLEHelper documentation and inspect the CommunityToolkit.WinUI.Helpers 8.x component layout to determine where source, samples, concept docs, and tests belong. Done means completing the Porting Basics and Quality Evaluation checklists, including configured targets, migrated tests, documentation, API review, and adequate test coverage.

Scritto dal modello di indicizzazione a partire dal testo della issue.