feat: add admin dashboard backend and deployment workflow

src/main/kotlin/me/wypark/blogbackend/api/controller/admin/AdminDashboardController.kt

@@ -0,0 +1,26 @@
+package me.wypark.blogbackend.api.controller.admin
+
+import me.wypark.blogbackend.api.common.ApiResponse
+import me.wypark.blogbackend.api.dto.AdminDashboardResponse
+import me.wypark.blogbackend.domain.dashboard.AdminDashboardService
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RequestParam
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+@RequestMapping("/api/admin/dashboard")
+class AdminDashboardController(
+    private val adminDashboardService: AdminDashboardService
+) {
+
+    @GetMapping
+    fun getDashboard(
+        @RequestParam(required = false) range: String?,
+        @RequestParam(required = false) timezone: String?
+    ): ResponseEntity<ApiResponse<AdminDashboardResponse>> {
+        val dashboard = adminDashboardService.getDashboard(range, timezone)
+        return ResponseEntity.ok(ApiResponse.success(dashboard, "OK"))
+    }
+}