feat: granular per-category push notification settings

New Settings → Notifications section with a toggle per category (follow,
comment, reply, reaction, rating, mention, leftover-expiring, shared
shopping list) — previously it was all-or-nothing (browser permission only).

userNotificationPrefs (one row per user, defaults all-on so existing users
see no behavior change until they opt out of something). Gated the push
send in the three places that dispatch one: lib/notifications.ts (the 6
in-app notification types), the leftover-expiry cron, and shopping-list-notify
— in-app notification-center entries and email are unaffected, this only
gates the push itself, matching the literal ask.

Verified locally: GET/PUT round-trips correctly, disabling a category
and confirming the settings page renders all 8 toggles.

packages/db/src/migrations/0034_dapper_nocturne.sql

@@ -0,0 +1,16 @@
+CREATE TABLE "user_notification_prefs" (
+	"id" text PRIMARY KEY NOT NULL,
+	"user_id" text NOT NULL,
+	"follow" boolean DEFAULT true NOT NULL,
+	"comment" boolean DEFAULT true NOT NULL,
+	"reply" boolean DEFAULT true NOT NULL,
+	"reaction" boolean DEFAULT true NOT NULL,
+	"rating" boolean DEFAULT true NOT NULL,
+	"mention" boolean DEFAULT true NOT NULL,
+	"leftover_expiring" boolean DEFAULT true NOT NULL,
+	"shopping_list" boolean DEFAULT true NOT NULL,
+	"updated_at" timestamp DEFAULT now() NOT NULL,
+	CONSTRAINT "user_notification_prefs_user_id_unique" UNIQUE("user_id")
+);
+--> statement-breakpoint
+ALTER TABLE "user_notification_prefs" ADD CONSTRAINT "user_notification_prefs_user_id_users_id_fk" FOREIGN KEY ("user_id") REFERENCES "public"."users"("id") ON DELETE cascade ON UPDATE no action;

packages/db/src/migrations/meta/_journal.json

@@ -239,6 +239,13 @@
       "when": 1783864805460,
       "tag": "0033_graceful_jetstream",
       "breakpoints": true
+    },
+    {
+      "idx": 34,
+      "version": "7",
+      "when": 1783875228288,
+      "tag": "0034_dapper_nocturne",
+      "breakpoints": true
     }
   ]
 }