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

internal/api/handlers_syncpairs.go

@@ -0,0 +1,183 @@
+package api
+
+import (
+	"database/sql"
+	"encoding/json"
+	"net/http"
+	"regexp"
+	"strconv"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/syncserver/internal/models"
+)
+
+type SyncPairHandler struct {
+	db *sql.DB
+}
+
+func NewSyncPairHandler(db *sql.DB) *SyncPairHandler {
+	return &SyncPairHandler{db: db}
+}
+
+var directionRegex = regexp.MustCompile(`^(push|pull|mirror)$`)
+
+func (h *SyncPairHandler) List(w http.ResponseWriter, r *http.Request) {
+	repo := models.NewSyncPairRepository(h.db)
+	pairs, err := repo.GetAll()
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to fetch sync pairs")
+		return
+	}
+	out := make([]SyncPairResponse, len(pairs))
+	for i, p := range pairs {
+		out[i] = syncPairToResp(p)
+	}
+	writeJSON(w, out)
+}
+
+func (h *SyncPairHandler) Get(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid id")
+		return
+	}
+	repo := models.NewSyncPairRepository(h.db)
+	p, err := repo.GetByID(id)
+	if err == sql.ErrNoRows {
+		writeError(w, http.StatusNotFound, "sync pair not found")
+		return
+	}
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to fetch sync pair")
+		return
+	}
+	writeJSON(w, syncPairToResp(*p))
+}
+
+func (h *SyncPairHandler) Create(w http.ResponseWriter, r *http.Request) {
+	var req SyncPairRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	if req.Name == "" || req.SourcePath == "" || req.DestPath == "" {
+		writeError(w, http.StatusBadRequest, "name, source_path and dest_path are required")
+		return
+	}
+	if req.Direction == "" {
+		req.Direction = "push"
+	}
+	if !directionRegex.MatchString(req.Direction) {
+		writeError(w, http.StatusBadRequest, "direction must be push, pull, or mirror")
+		return
+	}
+	if req.RsyncFlags == "" {
+		req.RsyncFlags = "-aP"
+	}
+	if !req.Enabled {
+		req.Enabled = true
+	}
+
+	sp := &models.SyncPair{
+		Name:            req.Name,
+		SourceMachineID: req.SourceMachineID,
+		SourcePath:      req.SourcePath,
+		DestMachineID:   req.DestMachineID,
+		DestPath:        req.DestPath,
+		Direction:       req.Direction,
+		RsyncFlags:      req.RsyncFlags,
+		ExcludePatterns: req.ExcludePatterns,
+		Enabled:         req.Enabled,
+	}
+
+	repo := models.NewSyncPairRepository(h.db)
+	id, err := repo.Create(sp)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to create sync pair")
+		return
+	}
+	sp.ID = id
+	w.Header().Set("Location", "/api/sync-pairs/"+strconv.FormatInt(id, 10))
+	writeJSON(w, syncPairToResp(*sp), http.StatusCreated)
+}
+
+func (h *SyncPairHandler) Update(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid id")
+		return
+	}
+
+	var req SyncPairRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	if req.Name == "" || req.SourcePath == "" || req.DestPath == "" {
+		writeError(w, http.StatusBadRequest, "name, source_path and dest_path are required")
+		return
+	}
+	if !directionRegex.MatchString(req.Direction) {
+		writeError(w, http.StatusBadRequest, "direction must be push, pull, or mirror")
+		return
+	}
+
+	repo := models.NewSyncPairRepository(h.db)
+	existing, err := repo.GetByID(id)
+	if err == sql.ErrNoRows {
+		writeError(w, http.StatusNotFound, "sync pair not found")
+		return
+	}
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to fetch sync pair")
+		return
+	}
+
+	existing.Name = req.Name
+	existing.SourceMachineID = req.SourceMachineID
+	existing.SourcePath = req.SourcePath
+	existing.DestMachineID = req.DestMachineID
+	existing.DestPath = req.DestPath
+	existing.Direction = req.Direction
+	existing.RsyncFlags = req.RsyncFlags
+	existing.ExcludePatterns = req.ExcludePatterns
+	existing.Enabled = req.Enabled
+
+	if err := repo.Update(existing); err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to update sync pair")
+		return
+	}
+	writeJSON(w, syncPairToResp(*existing))
+}
+
+func (h *SyncPairHandler) Delete(w http.ResponseWriter, r *http.Request) {
+	id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "invalid id")
+		return
+	}
+
+	repo := models.NewSyncPairRepository(h.db)
+	if err := repo.Delete(id); err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to delete sync pair")
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func syncPairToResp(p models.SyncPair) SyncPairResponse {
+	return SyncPairResponse{
+		ID:              p.ID,
+		Name:            p.Name,
+		SourceMachineID: p.SourceMachineID,
+		SourcePath:      p.SourcePath,
+		DestMachineID:   p.DestMachineID,
+		DestPath:        p.DestPath,
+		Direction:       p.Direction,
+		RsyncFlags:      p.RsyncFlags,
+		ExcludePatterns: p.ExcludePatterns,
+		Enabled:         p.Enabled,
+	}
+}