feat(server): meter AI point usage across tenant AI features

Adds an ai_point_usage_logs ledger and a reserve/refund/complete pipeline
that charges AI points for article selection optimize, template analyze
/title/outline, and KOL prompt generate/optimize. Pending reservations
are reconciled when the kol-assist worker and template-assist tasks
finish or fail, so points refund automatically on errors. Workspace now
exposes the AI quota status and a paginated usage ledger.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/tenant/transport/workspace_handler.go

@@ -22,6 +22,7 @@ func NewWorkspaceHandler(a *bootstrap.App) *WorkspaceHandler {
 				a.Cache,
 			),
 			repository.NewQuotaRepository(a.DB),
+			repository.NewAIPointUsageRepository(a.DB),
 		).WithCache(a.Cache),
 	}
 }
@@ -53,6 +54,30 @@ func (h *WorkspaceHandler) QuotaSummary(c *gin.Context) {
 	response.Success(c, data)
 }
 
+func (h *WorkspaceHandler) AIPointUsageLogs(c *gin.Context) {
+	page := parseIntQuery(c.Query("page"), 1)
+	pageSize := parseIntQuery(c.Query("page_size"), 20)
+	if c.Query("page") == "" && c.Query("page_size") == "" && c.Query("limit") != "" {
+		limit := parseIntQuery(c.Query("limit"), 20)
+		offset := parseIntQuery(c.Query("offset"), 0)
+		if limit > 0 {
+			pageSize = limit
+			page = offset/limit + 1
+		}
+	}
+
+	data, err := h.svc.AIPointUsageLogs(
+		c.Request.Context(),
+		page,
+		pageSize,
+	)
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	response.Success(c, data)
+}
+
 func (h *WorkspaceHandler) TemplateCards(c *gin.Context) {
 	data, err := h.svc.TemplateCards(c.Request.Context())
 	if err != nil {