fix: 三端联调测试 2 P0 + 6 P1 + 2 P2 修复

P0-1: SaaS relay 模型别名解析 — "glm-4-flash" → "glm-4-flash-250414" (resolve_model)
P0-2: config.rs interpolate_env_vars UTF-8 修复 (chars 迭代器替代 bytes as char)
      + DB 启动编码检查 + docker-compose UTF-8 编码参数

P1-3: UI 模型选择器覆盖 Agent 默认模型 (model_override 全链路: TS→Tauri→Rust kernel)
P1-6: 知识搜索管道修复 — seed_knowledge 创建 chunks + 默认分类 (seed/uploaded/distillation)
P1-7: 用量限额从当前 Plan 读取 (非 stale usage 表)
P1-8: relay 双维度配额检查 (relay_requests + input_tokens)

P2-9: SSE 路径 token 计数修复 — 流结束检测替代固定 500ms sleep + billing increment

crates/zclaw-saas/src/db.rs

@@ -38,10 +38,25 @@ pub async fn init_db(config: &DatabaseConfig) -> SaasResult<PgPool> {
         .connect(&database_url)
         .await?;
 
+    // 验证数据库编码为 UTF8 — 中文 Windows (GBK/代码页936) 可能导致默认非 UTF8
+    let encoding: (String,) = sqlx::query_as("SHOW server_encoding")
+        .fetch_one(&pool)
+        .await
+        .unwrap_or(("UNKNOWN".to_string(),));
+    if encoding.0.to_uppercase() != "UTF8" {
+        tracing::error!(
+            "⚠ 数据库编码为 '{}'，非 UTF8！中文数据将损坏。请使用 CREATE DATABASE ... WITH ENCODING='UTF8' 重建数据库。",
+            encoding.0
+        );
+    } else {
+        tracing::info!("Database encoding: {}", encoding.0);
+    }
+
     run_migrations(&pool).await?;
     ensure_security_columns(&pool).await?;
     seed_admin_account(&pool).await?;
     seed_builtin_prompts(&pool).await?;
+    seed_knowledge_categories(&pool).await?;
     seed_builtin_industries(&pool).await?;
     seed_demo_data(&pool).await?;
     fix_seed_data(&pool).await?;
@@ -1004,6 +1019,31 @@ async fn seed_builtin_industries(pool: &PgPool) -> SaasResult<()> {
     crate::industry::service::seed_builtin_industries(pool).await
 }
 
+/// 种子化知识库默认分类（幂等）
+async fn seed_knowledge_categories(pool: &PgPool) -> SaasResult<()> {
+    let now = chrono::Utc::now();
+    let categories = [
+        ("seed", "种子知识", "系统内置的行业基础知识"),
+        ("uploaded", "上传文档", "用户上传的文档知识"),
+        ("distillation", "蒸馏知识", "API 蒸馏生成的知识"),
+    ];
+    for (id, name, desc) in &categories {
+        sqlx::query(
+            "INSERT INTO knowledge_categories (id, name, description, created_at, updated_at) \
+             VALUES ($1, $2, $3, $4, $4) \
+             ON CONFLICT (id) DO NOTHING"
+        )
+        .bind(id)
+        .bind(name)
+        .bind(desc)
+        .bind(&now)
+        .execute(pool)
+        .await?;
+    }
+    tracing::debug!("Seeded knowledge categories");
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     // PostgreSQL 单元测试需要真实数据库连接，此处保留接口兼容