[management] Resolve agent network permissions per submodule (#7030)

## Describe your changes

Agent Network gates providers, policies, guardrails, budgets, usage,
access logs, and settings behind the single `agent_network` permission
module, so access is all-or-nothing: a future delegated role cannot be
scoped to a subset of the area (for example usage-only visibility).

This introduces dotted submodules (`agent_network.providers`,
`.policies`, `.guardrails`, `.budgets`, `.usage`, `.logs`, `.settings`)
and resolves grants with a cascade: exact module first, then its parent,
then the role's `AutoAllowNew` default. The agent network manager now
validates each operation against its matching submodule. `usage`
(aggregated counters, overview) is deliberately separate from `logs`
(request-level entries, which can contain captured prompts).

No role definitions change. No built-in role carries an explicit
`agent_network` entry, so every role resolves the submodules exactly as
it resolved the parent module before — pinned by a test that compares
each built-in role's answer on every submodule against its answer on
`agent_network`. Role additions that use these submodules come
separately.

management/server/permissions/manager.go

@@ -82,6 +82,9 @@ func (m *managerImpl) ValidateUserPermissions(
 	return m.ValidateRoleModuleAccess(ctx, accountID, role, module, operation), ctxEnriched, nil
 }
 
+// ValidateRoleModuleAccess resolves an operation against the role's explicit
+// grant for the module, then the grant for its parent module when the module
+// is a dotted submodule, and finally the role's AutoAllowNew default.
 func (m *managerImpl) ValidateRoleModuleAccess(
 	ctx context.Context,
 	accountID string,
@@ -89,7 +92,7 @@ func (m *managerImpl) ValidateRoleModuleAccess(
 	module modules.Module,
 	operation operations.Operation,
 ) bool {
-	if permissions, ok := role.Permissions[module]; ok {
+	if permissions, ok := lookupModulePermissions(role, module); ok {
 		if allowed, exists := permissions[operation]; exists {
 			return allowed
 		}
@@ -100,6 +103,21 @@ func (m *managerImpl) ValidateRoleModuleAccess(
 	return role.AutoAllowNew[operation]
 }
 
+// lookupModulePermissions returns the role's explicit permission set for the
+// module, falling back to the parent module's set for dotted submodules. The
+// second return reports whether any explicit set was found.
+func lookupModulePermissions(role roles.RolePermissions, module modules.Module) (map[operations.Operation]bool, bool) {
+	if permissions, ok := role.Permissions[module]; ok {
+		return permissions, true
+	}
+	if parent, hasParent := module.Parent(); hasParent {
+		if permissions, ok := role.Permissions[parent]; ok {
+			return permissions, true
+		}
+	}
+	return nil, false
+}
+
 func (m *managerImpl) ValidateAccountAccess(ctx context.Context, accountID string, user *types.User, allowOwnerAndAdmin bool) (context.Context, error) {
 	if user.AccountID != accountID {
 		return ctx, status.NewUserNotPartOfAccountError()
@@ -119,7 +137,7 @@ func (m *managerImpl) GetPermissionsByRole(ctx context.Context, role types.UserR
 	permissions := roles.Permissions{}
 
 	for k := range modules.All {
-		if rolePermissions, ok := roleMap.Permissions[k]; ok {
+		if rolePermissions, ok := lookupModulePermissions(roleMap, k); ok {
 			permissions[k] = rolePermissions
 			continue
 		}