feat: real-time staff messaging over Socket.io

Add conversations/participants/messages tables, a participant-scoped REST
API (/api/conversations) and a Socket.io server (session-authenticated
handshake; per-user + per-conversation rooms) sharing the HTTP port. New
messages broadcast live and create per-recipient notifications. Also lands
the notifications table + service + routes (used by the message flow). The
Messages page is rewritten: live threads, unread state, and a compose
dialog to start a conversation with a clinic member.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/drizzle/0006_square_wither.sql

@@ -0,0 +1,52 @@
+CREATE TABLE "conversation_participants" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"conversation_id" uuid NOT NULL,
+	"user_id" text NOT NULL,
+	"last_read_at" timestamp
+);
+--> statement-breakpoint
+CREATE TABLE "conversations" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"organization_id" text NOT NULL,
+	"name" text,
+	"is_group" boolean DEFAULT false NOT NULL,
+	"created_by" text,
+	"created_at" timestamp DEFAULT now() NOT NULL,
+	"updated_at" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE "messages" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"conversation_id" uuid NOT NULL,
+	"sender_id" text NOT NULL,
+	"body" text NOT NULL,
+	"created_at" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+CREATE TABLE "notifications" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"organization_id" text NOT NULL,
+	"user_id" text NOT NULL,
+	"type" text NOT NULL,
+	"text" text NOT NULL,
+	"read" boolean DEFAULT false NOT NULL,
+	"entity_type" text,
+	"entity_id" text,
+	"actor_name" text,
+	"actor_initials" text,
+	"created_at" timestamp DEFAULT now() NOT NULL
+);
+--> statement-breakpoint
+ALTER TABLE "conversation_participants" ADD CONSTRAINT "conversation_participants_conversation_id_conversations_id_fk" FOREIGN KEY ("conversation_id") REFERENCES "public"."conversations"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "conversation_participants" ADD CONSTRAINT "conversation_participants_user_id_user_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."user"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "conversations" ADD CONSTRAINT "conversations_organization_id_organization_id_fk" FOREIGN KEY ("organization_id") REFERENCES "public"."organization"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "conversations" ADD CONSTRAINT "conversations_created_by_user_id_fk" FOREIGN KEY ("created_by") REFERENCES "public"."user"("id") ON DELETE set null ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "messages" ADD CONSTRAINT "messages_conversation_id_conversations_id_fk" FOREIGN KEY ("conversation_id") REFERENCES "public"."conversations"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "messages" ADD CONSTRAINT "messages_sender_id_user_id_fk" FOREIGN KEY ("sender_id") REFERENCES "public"."user"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "notifications" ADD CONSTRAINT "notifications_organization_id_organization_id_fk" FOREIGN KEY ("organization_id") REFERENCES "public"."organization"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "notifications" ADD CONSTRAINT "notifications_user_id_user_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."user"("id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE UNIQUE INDEX "conv_participant_uidx" ON "conversation_participants" USING btree ("conversation_id","user_id");--> statement-breakpoint
+CREATE INDEX "conv_participant_user_idx" ON "conversation_participants" USING btree ("user_id");--> statement-breakpoint
+CREATE INDEX "conversations_org_idx" ON "conversations" USING btree ("organization_id");--> statement-breakpoint
+CREATE INDEX "messages_conv_idx" ON "messages" USING btree ("conversation_id","created_at");--> statement-breakpoint
+CREATE INDEX "notifications_org_user_read_idx" ON "notifications" USING btree ("organization_id","user_id","read");

backend/drizzle/meta/_journal.json

@@ -43,6 +43,13 @@
       "when": 1780850717058,
       "tag": "0005_true_gwen_stacy",
       "breakpoints": true
+    },
+    {
+      "idx": 6,
+      "version": "7",
+      "when": 1780856647280,
+      "tag": "0006_square_wither",
+      "breakpoints": true
     }
   ]
 }