Add complete database schema and ORM models

Schema (002_tables.sql):
- users: accounts with nick, password hash, timestamps
- auth_tokens: per-device tokens with expiry, linked to users
- channels: chat rooms with topic and mode flags
- channel_members: membership with per-user modes (+o, +v)
- messages: channel/DM history with structured JSON meta
- message_queue: per-user pending delivery queue
- sessions: server-held session state with idle timeout
- server_links: federation peer configuration

Models (internal/models/):
- All models embed Base for database access
- Relation methods on models: User.Channels(), User.QueuedMessages(),
  Channel.Members(), Channel.RecentMessages(), ChannelMember.User(),
  ChannelMember.Channel(), AuthToken.User(), Session.User()
- IDs are UUIDs (TEXT), not auto-increment integers
- JSON tags use camelCase per lint rules

All tables verified: migrations apply cleanly, 0 lint issues.

internal/models/channel.go

@@ -1,6 +1,7 @@
 package models
 
 import (
+	"context"
 	"time"
 )
 
@@ -8,10 +9,88 @@ import (
 type Channel struct {
 	Base
 
-	ID        int64     `json:"id"`
+	ID        string    `json:"id"`
 	Name      string    `json:"name"`
 	Topic     string    `json:"topic"`
 	Modes     string    `json:"modes"`
 	CreatedAt time.Time `json:"createdAt"`
 	UpdatedAt time.Time `json:"updatedAt"`
 }
+
+// Members returns all users who are members of this channel.
+func (c *Channel) Members(ctx context.Context) ([]*ChannelMember, error) {
+	rows, err := c.GetDB().QueryContext(ctx, `
+		SELECT cm.channel_id, cm.user_id, cm.modes, cm.joined_at,
+		       u.nick
+		FROM channel_members cm
+		JOIN users u ON u.id = cm.user_id
+		WHERE cm.channel_id = ?
+		ORDER BY cm.joined_at`,
+		c.ID,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var members []*ChannelMember
+
+	for rows.Next() {
+		m := &ChannelMember{}
+		m.SetDB(c.db)
+
+		err = rows.Scan(
+			&m.ChannelID, &m.UserID, &m.Modes,
+			&m.JoinedAt, &m.Nick,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		members = append(members, m)
+	}
+
+	return members, rows.Err()
+}
+
+// RecentMessages returns the most recent messages in this channel.
+func (c *Channel) RecentMessages(
+	ctx context.Context,
+	limit int,
+) ([]*Message, error) {
+	rows, err := c.GetDB().QueryContext(ctx, `
+		SELECT id, ts, from_user_id, from_nick,
+		       target, type, body, meta, created_at
+		FROM messages
+		WHERE target = ?
+		ORDER BY ts DESC
+		LIMIT ?`,
+		c.Name, limit,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	defer func() { _ = rows.Close() }()
+
+	var messages []*Message
+
+	for rows.Next() {
+		msg := &Message{}
+		msg.SetDB(c.db)
+
+		err = rows.Scan(
+			&msg.ID, &msg.Timestamp, &msg.FromUserID,
+			&msg.FromNick, &msg.Target, &msg.Type,
+			&msg.Body, &msg.Meta, &msg.CreatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		messages = append(messages, msg)
+	}
+
+	return messages, rows.Err()
+}