Add Phase 2: Local SQLite database with sync functionality

Implements complete offline-first architecture with SQLite caching and MariaDB synchronization.

Key features:
- Local SQLite database for offline operation (data/quoteforge.db)
- Connection settings with encrypted credentials
- Component and pricelist caching with auto-sync
- Sync API endpoints (/api/sync/status, /components, /pricelists, /all)
- Real-time sync status indicator in UI with auto-refresh
- Offline mode detection middleware
- Migration tool for database initialization
- Setup wizard for initial configuration

New components:
- internal/localdb: SQLite repository layer (components, pricelists, sync)
- internal/services/sync: Synchronization service
- internal/handlers/sync: Sync API handlers
- internal/handlers/setup: Setup wizard handlers
- internal/middleware/offline: Offline detection
- cmd/migrate: Database migration tool

UI improvements:
- Setup page for database configuration
- Sync status indicator with online/offline detection
- Warning icons for pending synchronization
- Auto-refresh every 30 seconds

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

internal/handlers/pricelist.go

@@ -0,0 +1,134 @@
+package handlers
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+	"git.mchus.pro/mchus/quoteforge/internal/localdb"
+	"git.mchus.pro/mchus/quoteforge/internal/services/pricelist"
+)
+
+type PricelistHandler struct {
+	service *pricelist.Service
+	localDB *localdb.LocalDB
+}
+
+func NewPricelistHandler(service *pricelist.Service, localDB *localdb.LocalDB) *PricelistHandler {
+	return &PricelistHandler{service: service, localDB: localDB}
+}
+
+// List returns all pricelists with pagination
+func (h *PricelistHandler) List(c *gin.Context) {
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	perPage, _ := strconv.Atoi(c.DefaultQuery("per_page", "20"))
+
+	pricelists, total, err := h.service.List(page, perPage)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"pricelists": pricelists,
+		"total":      total,
+		"page":       page,
+		"per_page":   perPage,
+	})
+}
+
+// Get returns a single pricelist by ID
+func (h *PricelistHandler) Get(c *gin.Context) {
+	idStr := c.Param("id")
+	id, err := strconv.ParseUint(idStr, 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid pricelist ID"})
+		return
+	}
+
+	pl, err := h.service.GetByID(uint(id))
+	if err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "pricelist not found"})
+		return
+	}
+
+	c.JSON(http.StatusOK, pl)
+}
+
+// Create creates a new pricelist from current prices
+func (h *PricelistHandler) Create(c *gin.Context) {
+	// Get the database username as the creator
+	createdBy := h.localDB.GetDBUser()
+	if createdBy == "" {
+		createdBy = "unknown"
+	}
+
+	pl, err := h.service.CreateFromCurrentPrices(createdBy)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusCreated, pl)
+}
+
+// Delete deletes a pricelist by ID
+func (h *PricelistHandler) Delete(c *gin.Context) {
+	idStr := c.Param("id")
+	id, err := strconv.ParseUint(idStr, 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid pricelist ID"})
+		return
+	}
+
+	if err := h.service.Delete(uint(id)); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{"message": "pricelist deleted"})
+}
+
+// GetItems returns items for a pricelist with pagination
+func (h *PricelistHandler) GetItems(c *gin.Context) {
+	idStr := c.Param("id")
+	id, err := strconv.ParseUint(idStr, 10, 32)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid pricelist ID"})
+		return
+	}
+
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	perPage, _ := strconv.Atoi(c.DefaultQuery("per_page", "50"))
+	search := c.Query("search")
+
+	items, total, err := h.service.GetItems(uint(id), page, perPage, search)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"items":    items,
+		"total":    total,
+		"page":     page,
+		"per_page": perPage,
+	})
+}
+
+// CanWrite returns whether the current user can create pricelists
+func (h *PricelistHandler) CanWrite(c *gin.Context) {
+	canWrite, debugInfo := h.service.CanWriteDebug()
+	c.JSON(http.StatusOK, gin.H{"can_write": canWrite, "debug": debugInfo})
+}
+
+// GetLatest returns the most recent active pricelist
+func (h *PricelistHandler) GetLatest(c *gin.Context) {
+	pl, err := h.service.GetLatestActive()
+	if err != nil {
+		c.JSON(http.StatusNotFound, gin.H{"error": "no active pricelists found"})
+		return
+	}
+
+	c.JSON(http.StatusOK, pl)
+}