feat: 新增资产拦截规则（全局黑名单）增删改查

新增独立于命令拦截(intercept_rules)的资产拦截功能，仅提供规则的
存储与管理；具体匹配/拦截逻辑另行实现。

- db: 新增 asset_intercept_rules 表(schema.sql，幂等)与 CRUD 层
  (db/asset_intercept.go)；kind 支持全等/模糊的 域名·IP·URL 及 CIDR
- db: 首启动 seed 内置模糊拦截政府(.gov/.gov.cn)与教育(.edu/.edu.cn)
  网站，settings 标记位门控，可禁用/删除且重启不复活
- server: /api/asset-intercept/rules 的 list/create/update/delete/toggle；
  cidr、exact_ip 做格式校验
- web: 新增「资产拦截」页(/system/intercept/assets)与侧边栏入口、
  api 与类型定义

db/db.go

@@ -261,9 +261,41 @@ ON CONFLICT (name) DO NOTHING`,
 	if err := d.seedDefaultInterceptRulesV2(); err != nil {
 		return fmt.Errorf("seed intercept rules v2: %w", err)
 	}
+	if err := d.seedDefaultAssetInterceptRules(); err != nil {
+		return fmt.Errorf("seed asset intercept rules: %w", err)
+	}
 	return nil
 }
 
+// seedDefaultAssetInterceptRules inserts the built-in asset blocklist (fuzzy
+// domain matches for government / education sites) once on first startup. Gated
+// by a settings flag so a user's later disable/delete is never resurrected on
+// restart — same policy as the intercept-rule seed.
+func (d *DB) seedDefaultAssetInterceptRules() error {
+	if v, _, _ := d.GetSetting("asset_intercept_default_rules_v1"); v == "done" {
+		return nil
+	}
+	rules := []struct {
+		kind    string
+		pattern string
+		note    string
+	}{
+		{"fuzzy_domain", ".gov", "[内置] 政府网站 (.gov)"},
+		{"fuzzy_domain", ".gov.cn", "[内置] 政府网站 (.gov.cn)"},
+		{"fuzzy_domain", ".edu", "[内置] 教育网站 (.edu)"},
+		{"fuzzy_domain", ".edu.cn", "[内置] 教育网站 (.edu.cn)"},
+	}
+	for _, r := range rules {
+		if _, err := d.Exec(`
+INSERT INTO asset_intercept_rules(enabled, kind, pattern, note, builtin)
+VALUES (true, $1, $2, $3, true)
+ON CONFLICT DO NOTHING`, r.kind, r.pattern, r.note); err != nil {
+			return fmt.Errorf("asset rule %q: %w", r.pattern, err)
+		}
+	}
+	return d.SetSetting("asset_intercept_default_rules_v1", "done")
+}
+
 // builtinSkillVisibility maps a shipped skill's directory name → the built-in
 // agent keys that should see it by default. The skill FILES themselves live on the
 // filesystem (SkillDir, loaded by norma at runtime); DB only carries this visibility