[BACKEND] Initialize Go backend structure and dependencies (#23)

migrations/001_initial.sql

@@ -1,125 +0,0 @@
--- ==========================================
--- Chat Switchboard - Initial Schema
--- ==========================================
--- PostgreSQL migration for backend support
-
--- Enable UUID extension
-CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
-
--- Users table (optional, for multi-user support)
-CREATE TABLE users (
-    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
-    email VARCHAR(255) UNIQUE,
-    password_hash VARCHAR(255),
-    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
-    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
-);
-
--- API configurations per user
-CREATE TABLE api_configs (
-    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
-    user_id UUID REFERENCES users(id) ON DELETE CASCADE,
-    name VARCHAR(100) NOT NULL DEFAULT 'default',
-    endpoint VARCHAR(500) NOT NULL,
-    api_key_encrypted TEXT NOT NULL,
-    is_default BOOLEAN DEFAULT FALSE,
-    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
-    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
-    UNIQUE(user_id, name)
-);
-
--- User settings
-CREATE TABLE user_settings (
-    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
-    user_id UUID UNIQUE REFERENCES users(id) ON DELETE CASCADE,
-    default_model VARCHAR(100) DEFAULT 'gpt-3.5-turbo',
-    stream_responses BOOLEAN DEFAULT TRUE,
-    show_thinking BOOLEAN DEFAULT TRUE,
-    system_prompt TEXT,
-    max_tokens INTEGER DEFAULT 4096,
-    temperature DECIMAL(3,2) DEFAULT 0.7,
-    top_p DECIMAL(3,2) DEFAULT 1.0,
-    presence_penalty DECIMAL(3,2) DEFAULT 0.0,
-    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
-    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
-);
-
--- Chats
-CREATE TABLE chats (
-    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
-    user_id UUID REFERENCES users(id) ON DELETE CASCADE,
-    title VARCHAR(255) NOT NULL,
-    model VARCHAR(100),
-    api_config_id UUID REFERENCES api_configs(id) ON DELETE SET NULL,
-    is_archived BOOLEAN DEFAULT FALSE,
-    is_pinned BOOLEAN DEFAULT FALSE,
-    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
-    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
-);
-
--- Messages
-CREATE TABLE messages (
-    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
-    chat_id UUID NOT NULL REFERENCES chats(id) ON DELETE CASCADE,
-    role VARCHAR(20) NOT NULL CHECK (role IN ('system', 'user', 'assistant')),
-    content TEXT NOT NULL,
-    model VARCHAR(100),
-    tokens_used INTEGER,
-    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
-);
-
--- Cached models per API config
-CREATE TABLE cached_models (
-    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
-    api_config_id UUID NOT NULL REFERENCES api_configs(id) ON DELETE CASCADE,
-    model_id VARCHAR(100) NOT NULL,
-    owned_by VARCHAR(100),
-    cached_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
-    UNIQUE(api_config_id, model_id)
-);
-
--- Indexes for performance
-CREATE INDEX idx_chats_user_id ON chats(user_id);
-CREATE INDEX idx_chats_updated_at ON chats(updated_at DESC);
-CREATE INDEX idx_messages_chat_id ON messages(chat_id);
-CREATE INDEX idx_messages_created_at ON messages(created_at);
-CREATE INDEX idx_api_configs_user_id ON api_configs(user_id);
-
--- Updated at trigger function
-CREATE OR REPLACE FUNCTION update_updated_at_column()
-RETURNS TRIGGER AS $$
-BEGIN
-    NEW.updated_at = NOW();
-    RETURN NEW;
-END;
-$$ language 'plpgsql';
-
--- Apply updated_at triggers
-CREATE TRIGGER update_users_updated_at BEFORE UPDATE ON users
-    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
-
-CREATE TRIGGER update_api_configs_updated_at BEFORE UPDATE ON api_configs
-    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
-
-CREATE TRIGGER update_user_settings_updated_at BEFORE UPDATE ON user_settings
-    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
-
-CREATE TRIGGER update_chats_updated_at BEFORE UPDATE ON chats
-    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
-
--- View for chat list with message count
-CREATE VIEW chat_list AS
-SELECT 
-    c.id,
-    c.user_id,
-    c.title,
-    c.model,
-    c.is_archived,
-    c.is_pinned,
-    c.created_at,
-    c.updated_at,
-    COUNT(m.id) as message_count,
-    MAX(m.created_at) as last_message_at
-FROM chats c
-LEFT JOIN messages m ON m.chat_id = c.id
-GROUP BY c.id;