Add source-bound Windows BLE preview - #56

Summary

• Add a generated Windows desktop runner and a WinRT BLE adapter for scan, connect, GATT, bond-state, pair, and remove-bond operations.
• Use the same durable CgmBondTransferSession Move flow as Android; no unsafeAdmin bond deletion.
• Add a portable Windows ZIP packager and an immutable-tag manual preview workflow.
• Suppress the WinRT plugin's raw native Bluetooth debug output at compile time.
• Store app state in non-roaming LocalAppData and document Windows preview limits.

Verification

• Full pre-push make check passed.
• 490 package/app unit and widget tests passed during integration, plus the integration demo.
• Format, analyzers, ShellCheck, actionlint, workflow contracts, Android/web/iOS builds, signing fail-closed checks, and native iOS tests passed.
• This PR's Windows Preview workflow must prove the Windows native compile, packaging, and native log suppression.

Preview limits

• Windows support remains a preview until physical AiDEX scan, pairing, authenticated session, readings, reconnect, and Move evidence is recorded.
• The preview bundle is unsigned.
• FlutterBluePlus open-use terms cover personal/nonprofit/educational use; commercial distribution needs its commercial license.
• The workflow does not create or modify a GitHub Release. A verified exact-tag ZIP can later be attached to the same stable v0.1.3 Release.