feat: complete SyncServer implementation

Full-stack Go monolith with embedded React frontend for orchestrating
rsync-over-SSH file synchronization with Wake-on-LAN support.

Features:
- JWT auth (HS256) with bcrypt password hashing
- CRUD for machines (with WoL config) and sync_pairs
- Ed25519 SSH key generation and known_hosts management
- WoL magic packet sender + TCP-connect waiter with backoff
- Sync engine: rsync subprocess, per-pair job queue, progress parsing
- Homebrew cron parser for scheduled syncs
- SSE stream for live job status (queued/waking_up/running/success/failed)
- React+TS+Vite+Tailwind SPA embedded via embed.FS
- Debian packaging with systemd unit, postinst/prerm/postrm

Tech stack:
- Go 1.22+ (CGO_ENABLED=0, pure SQLite via modernc.org/sqlite)
- chi router for HTTP API
- TypeScript + React 18 + Tailwind CSS frontend
- Cross-compiled to Linux amd64 for Proxmox LXC deployment

Tests: wol (MAC parsing, magic packet), syncengine/queue, scheduler/cron

packaging/debian/DEBIAN/control

@@ -0,0 +1,12 @@
+Package: syncserver
+Version: 1a66ac5
+Architecture: amd64
+Section: net
+Priority: optional
+Depends: rsync, openssh-client, ca-certificates
+Maintainer: SyncServer Team <syncserver@example.com>
+Description: Self-hosted file sync orchestrator with Wake-on-LAN and web UI
+ SyncServer is a Go-based server that provides a web interface to manage
+ and execute file synchronizations between multiple machines using rsync
+ over SSH, with optional Wake-on-LAN support to power on remote machines
+ before syncing.