feat: 添加公告系统（支持SQLite和PostgreSQL） (#129)

* feat(announcement): add database schema for SQLite and PostgreSQL

Add announcement table with id, title, content, enabled, created_at, updated_at columns to both SQLite and PostgreSQL schemas to support announcement system.

* feat(announcement): implement SQLite repository for announcement management

Add announcement CRUD operations in SQLite repository including create, read, update, delete, and list methods with proper error handling.

* feat(announcement): add HTTP handlers and auth middleware for announcement API

Implement admin-only update endpoint and public read endpoint for announcements. Add auth middleware to enforce admin-only access for update operations.

* feat(announcement): add frontend API client for announcement endpoints

Implement API client methods for fetching announcements and updating announcement settings with proper error handling.

* feat(announcement): add announcement display component to dashboard

Implement announcement display section in dashboard with real-time updates and proper styling using HeroUI components.

* feat(announcement): add announcement management UI to config page

Implement announcement settings panel with enable/disable toggle and content editor for admin users to manage announcements.

go-backend/internal/store/sqlite/repository.go

@@ -66,6 +66,14 @@ type ViteConfig struct {
 	Time  int64  `json:"time"`
 }
 
+type Announcement struct {
+	ID          int64         `json:"id"`
+	Content     string        `json:"content"`
+	Enabled     int           `json:"enabled"`
+	CreatedTime int64         `json:"created_time"`
+	UpdatedTime sql.NullInt64 `json:"updated_time,omitempty"`
+}
+
 type UserTunnelDetail struct {
 	ID            int64
 	UserID        int64
@@ -319,6 +327,46 @@ func (r *Repository) UpsertConfig(name, value string, now int64) error {
 	return err
 }
 
+func (r *Repository) GetAnnouncement() (*Announcement, error) {
+	if r == nil || r.db == nil {
+		return nil, errors.New("repository not initialized")
+	}
+
+	row := r.db.QueryRow(`SELECT id, content, enabled, created_time, updated_time FROM announcement ORDER BY id DESC LIMIT 1`)
+	ann := &Announcement{}
+	if err := row.Scan(&ann.ID, &ann.Content, &ann.Enabled, &ann.CreatedTime, &ann.UpdatedTime); err != nil {
+		if errors.Is(err, sql.ErrNoRows) {
+			return nil, nil
+		}
+		return nil, err
+	}
+	return ann, nil
+}
+
+func (r *Repository) UpsertAnnouncement(content string, enabled int, now int64) error {
+	if r == nil || r.db == nil {
+		return errors.New("repository not initialized")
+	}
+
+	var count int
+	err := r.db.QueryRow(`SELECT COUNT(*) FROM announcement`).Scan(&count)
+	if err != nil {
+		return err
+	}
+
+	if count == 0 {
+		_, err = r.db.Exec(`
+			INSERT INTO announcement(content, enabled, created_time, updated_time)
+			VALUES(?, ?, ?, ?)
+		`, content, enabled, now, now)
+	} else {
+		_, err = r.db.Exec(`
+			UPDATE announcement SET content = ?, enabled = ?, updated_time = ?
+		`, content, enabled, now)
+	}
+	return err
+}
+
 func (r *Repository) GetUserByID(id int64) (*User, error) {
 	if r == nil || r.db == nil {
 		return nil, errors.New("repository not initialized")

go-backend/internal/store/sqlite/sql/schema.sql

@@ -244,3 +244,11 @@ CREATE TABLE IF NOT EXISTS federation_tunnel_binding (
 
 CREATE UNIQUE INDEX IF NOT EXISTS idx_federation_tunnel_binding_unique ON federation_tunnel_binding(tunnel_id, node_id, chain_type, hop_inx);
 CREATE INDEX IF NOT EXISTS idx_federation_tunnel_binding_tunnel ON federation_tunnel_binding(tunnel_id, status);
+
+CREATE TABLE IF NOT EXISTS announcement (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  content TEXT NOT NULL,
+  enabled INTEGER NOT NULL DEFAULT 1,
+  created_time INTEGER NOT NULL,
+  updated_time INTEGER
+);