feat: add in-app notifications with Inngest queue integration

- Add notifications table schema (Drizzle migration 0002)
- Add Notification domain model and NotificationType to domain-models.ts
- Add notifications to DatabaseTableName enum and persistence repositories
- Add optional INNGEST_EVENT_KEY/INNGEST_SIGNING_KEY to env.ts
- Create Inngest client + persistNotificationFn in src/lib/inngest.ts
- Add Inngest API route at /api/inngest
- Create notification input schema and actions (list, markRead, markAllRead, unreadCount)
- Update createMyComment to resolve recipient and send notification events
- Update toogleReaction insert path to send notification events
- Replace notifications dashboard stub with full TanStack Query UI
- Add i18n strings to bn.json for notification copy

Agent-Logs-Url: https://github.com/techdiary-dev/techdiary.dev/sessions/a4d2f56f-8ea0-484d-883e-4aa0cce5a9cc

Co-authored-by: shoaibsharif <29075110+shoaibsharif@users.noreply.github.com>

Author: Copilot

migrations/0002_fearless_tomas.sql

@@ -0,0 +1,34 @@
+CREATE TABLE "gist_files" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"gist_id" uuid NOT NULL,
+	"filename" varchar NOT NULL,
+	"content" text NOT NULL,
+	"language" varchar,
+	"created_at" timestamp DEFAULT now(),
+	"updated_at" timestamp DEFAULT now()
+);
+--> statement-breakpoint
+CREATE TABLE "gists" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"title" varchar NOT NULL,
+	"description" text,
+	"is_public" boolean DEFAULT true,
+	"owner_id" uuid NOT NULL,
+	"created_at" timestamp DEFAULT now(),
+	"updated_at" timestamp DEFAULT now()
+);
+--> statement-breakpoint
+CREATE TABLE "notifications" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"recipient_id" uuid NOT NULL,
+	"actor_id" uuid,
+	"type" varchar(100) NOT NULL,
+	"payload" jsonb,
+	"read_at" timestamp,
+	"created_at" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+ALTER TABLE "gist_files" ADD CONSTRAINT "gist_files_gist_id_gists_id_fk" FOREIGN KEY ("gist_id") REFERENCES "public"."gists"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "gists" ADD CONSTRAINT "gists_owner_id_users_id_fk" FOREIGN KEY ("owner_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "notifications" ADD CONSTRAINT "notifications_recipient_id_users_id_fk" FOREIGN KEY ("recipient_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "notifications" ADD CONSTRAINT "notifications_actor_id_users_id_fk" FOREIGN KEY ("actor_id") REFERENCES "public"."users"("id") ON DELETE set null ON UPDATE no action;