feat: Implement comments, notifications, and custom emojis with new API routes, UI components, and database migrations.

migration_comments.sql

@@ -0,0 +1,37 @@
+-- Create comments table
+CREATE TABLE IF NOT EXISTS comments (
+    id SERIAL PRIMARY KEY,
+    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
+    user_id INTEGER NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
+    parent_id INTEGER REFERENCES comments(id) ON DELETE SET NULL,
+    content TEXT NOT NULL,
+    is_deleted BOOLEAN DEFAULT FALSE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE,
+    vote_score INTEGER DEFAULT 0
+);
+
+-- Create notifications table
+CREATE TABLE IF NOT EXISTS notifications (
+    id SERIAL PRIMARY KEY,
+    user_id INTEGER NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
+    type VARCHAR(32) NOT NULL, -- 'reply', 'comment', 'mention'
+    reference_id INTEGER NOT NULL, -- ID of the comment
+    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
+    is_read BOOLEAN DEFAULT FALSE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Create comment_subscriptions table (for subscribing to posts)
+CREATE TABLE IF NOT EXISTS comment_subscriptions (
+    user_id INTEGER NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
+    item_id INTEGER NOT NULL REFERENCES items(id) ON DELETE CASCADE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    PRIMARY KEY (user_id, item_id)
+);
+
+-- Indexes for performance
+CREATE INDEX idx_comments_item_id ON comments(item_id);
+CREATE INDEX idx_comments_user_id ON comments(user_id);
+CREATE INDEX idx_notifications_user_id ON notifications(user_id);
+CREATE INDEX idx_notifications_unread ON notifications(user_id) WHERE is_read = FALSE;