Scaffold C# native app

[enaboapps]

Summary

• add the C#/.NET 8 solution skeleton for the native 0.2.0 app
• port protocol validation, pairing/auth storage, settings normalization, startup registration, update logic, diagnostics, and view-model copy helpers
• add WPF main/settings window shells plus tray and startup-hidden lifecycle wiring
• bring the C# main window closer to the original Electron card UI with status badge, centered primary state, update banner, pairing panel, and collapsed troubleshooting
• refine C# WPF visual design with explicit rounded control templates and a custom sidebar-tabbed Settings utility layout
• wire WPF settings controls for startup, pointer movement, cursor overlay, updates, paired-device display, and forget-device actions
• wire the main-window update banner to open Settings > Updates and consume shared update state
• emit C# startup diagnostics to the existing app data JSONL path
• add a C# control-session routing layer for authenticated protocol commands and no-ack responses
• add C# pairing approval manager with deterministic verification codes, token-free pending views, accept/reject/expiry, and persisted paired devices
• show pending pairing approvals in the native main window with accept/reject actions
• expire stale C# pairing approvals at runtime, send expiry responses, close stale pairing connections, and clear expired Bluetooth partial frames
• add remote-session coordinator for pairing requests, delayed pairing-complete responses, replacement/expiry cleanup, and command delegation
• add Bluetooth remote-frame processor that maps remote-session outgoing messages back to response frames per connection
• port the Windows Bluetooth GATT host into the C# app process with live system radio monitoring, advertising restart, RX/TX/status characteristics, and typed Bluetooth events
• restart C# Bluetooth advertising after normal client disconnects so Android can reconnect after the first session
• allow smaller pointer movement scale values down to 25% and expose lower native Settings presets
• start the C# Bluetooth runtime from the WPF app and route incoming frames through the remote session to desktop input
• integrate an in-process C# cursor overlay runtime with click/move/drag rendering, crosshairs, persistent follow mode, and settings-backed color/size/visibility
• match C# cursor overlay while-controlling lifetime to the Electron control-session behavior
• fix C# cursor overlay startup race that crashed before the WinForms overlay handle existed
• fix C# single-file WPF startup by self-extracting native runtime libraries
• add C# Windows packaging scaffolding: NSIS installer script, dotnet publish/stage/package driver, updater metadata generation, and staged package verifier
• make the C# app project version the source of truth for C# executable, package, builder metadata, and updater metadata versions
• harden C# installer process detection and verify elevation, Program Files install target, run-after-finish behavior, app-close prompts, and uninstall registry metadata before packaging
• add CI coverage for C# restore, build, tests, stage-only package generation, and staged package verification
• expand C# Android-facing remote command coverage for shortcut, text, media, and window commands
• cover C# update polling guards for duplicate starts, stop/dispose, and overlapping automatic checks
• harden C# GitHub update backend coverage for newer-release selection and installer cache path safety
• add C# update install confirmation before opening the downloaded installer and test install failure copy
• signal the primary C# instance to show its main window from second normal launches while second --start-hidden launches still exit quietly
• add C# tray status and disconnect controls backed by live Bluetooth status
• show C# Bluetooth last-checked and last-changed timestamps in troubleshooting details
• expand C# Bluetooth troubleshooting summaries with event timestamps, recent event history, and recent error details
• keep the existing Electron app intact while C# parity work continues

Closes #279.

Validation

• npm run dotnet:restore
• npm run dotnet:build
• npm run dotnet:test (224 C# unit tests + 1 integration placeholder)
• npm run dotnet:publish
• npm run dotnet:package:win:stage
• npm run dotnet:package:win:verify
• staged C# app --start-hidden smoke
• staged C# app executable version check: FileVersion 0.2.0.0, ProductVersion 0.2.0
• staged C# builder metadata check: version: 0.2.0
• published C# app --start-hidden smoke after Bluetooth and overlay runtime startup
• published C# app startup diagnostics append smoke
• staged C# app launch smoke after reconnect fix: PID remained running, no startup crash events
• staged C# app launch smoke after WPF single-file extraction fix: PID remained running
• staged C# app launch smoke after main-window UI parity pass: PID remained running
• staged C# app launch smoke after WPF visual design pass: PID remained running
• staged C# app launch smoke after Settings layout correction: PID remained running
• staged C# app launch smoke after custom tabbed Settings restoration: PID remained running
• npm test
• npm run typecheck
• npm run build

Remaining parity work

• harden and manually smoke the in-process Bluetooth GATT host against Android on Windows hardware
• manually smoke cursor overlay rendering during real pointer input
• run C# NSIS installer build/signing on the signing runner with NSIS installed
• switch the production release workflow from Electron packaging to the C# installer once parity is accepted
• run full Windows manual parity smoke before replacing the Electron production target