refactor: rename mascot to chatbot across entire codebase

- Backend: mascot-chat module → chatbot, routes /mascot/chat → /chat
- Shared schema: pgMascotChatMessagesTable → pgChatbotMessagesTable
- Frontend: MascotProvider/useMascot → ChatbotProvider/useChatbot
- Gateway schema: update exports to match shared schema
- Docs: update all .md references (CLAUDE.md, README, specs, plans)
- All API routes, controller names, service classes, types renamed

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

services/frontend/src/components/shared/detail-stat.tsx

@@ -1,42 +0,0 @@
-import { Card, CardContent } from "@/components/ui/card";
-import { formatNumber } from "@/lib/format";
-import { cn } from "@/lib/utils";
-
-interface DetailStatProps {
-  label: string;
-  value: number;
-  variant?: "default" | "danger" | "success";
-  suffix?: string;
-}
-
-const valueColor = {
-  default: "",
-  danger: "text-red-400",
-  success: "text-emerald-400",
-};
-
-/**
- * Small stat label used inside detail views.
- */
-export function DetailStat({
-  label,
-  value,
-  variant = "default",
-  suffix,
-}: DetailStatProps) {
-  return (
-    <Card className="bg-gradient-to-br from-cyan-500/5 to-transparent border-cyan-500/10">
-      <CardContent className="p-3">
-        <p className="text-xs text-muted-foreground/70 tracking-wide">
-          {label}
-        </p>
-        <p
-          className={cn("text-lg font-bold tabular-nums", valueColor[variant])}
-        >
-          {formatNumber(value)}
-          {suffix}
-        </p>
-      </CardContent>
-    </Card>
-  );
-}

services/frontend/src/components/shared/stat-card.tsx

@@ -1,78 +0,0 @@
-import type { LucideIcon } from "lucide-react";
-
-import { Card, CardContent } from "@/components/ui/card";
-import { formatNumber } from "@/lib/format";
-import { cn } from "@/lib/utils";
-
-interface StatCardProps {
-  label: string;
-  value: number;
-  icon: LucideIcon;
-  variant?: "default" | "danger" | "success" | "warning";
-}
-
-const variantStyles = {
-  default: "from-cyan-500/10 to-teal-500/5 border-cyan-500/20",
-  danger: "from-red-500/10 to-rose-500/5 border-red-500/20",
-  success: "from-emerald-500/10 to-green-500/5 border-emerald-500/20",
-  warning: "from-amber-500/10 to-yellow-500/5 border-amber-500/20",
-};
-
-const iconBg = {
-  default: "bg-cyan-500/15 text-cyan-400",
-  danger: "bg-red-500/15 text-red-400",
-  success: "bg-emerald-500/15 text-emerald-400",
-  warning: "bg-amber-500/15 text-amber-400",
-};
-
-const valueColor = {
-  default: "",
-  danger: "text-red-400",
-  success: "text-emerald-400",
-  warning: "text-amber-400",
-};
-
-/**
- * Metric card used across dashboard and landing pages.
- */
-export function StatCard({
-  label,
-  value,
-  icon: Icon,
-  variant = "default",
-}: StatCardProps) {
-  return (
-    <Card
-      className={cn(
-        "border bg-gradient-to-br backdrop-blur-sm",
-        variantStyles[variant],
-      )}
-    >
-      <CardContent className="p-4">
-        <div className="flex items-start justify-between">
-          <div className="space-y-1.5">
-            <p className="text-xs text-muted-foreground/80 tracking-wide">
-              {label}
-            </p>
-            <p
-              className={cn(
-                "text-2xl font-bold tabular-nums tracking-tight",
-                valueColor[variant],
-              )}
-            >
-              {formatNumber(value)}
-            </p>
-          </div>
-          <div
-            className={cn(
-              "flex size-9 shrink-0 items-center justify-center rounded-lg",
-              iconBg[variant],
-            )}
-          >
-            <Icon className="size-4" />
-          </div>
-        </div>
-      </CardContent>
-    </Card>
-  );
-}