fix: address PR #111 review feedback

- Extract validateWorkspaceSegment to commands/init/validate.ts
- Unify splitProviderModelRef in config/, used by both resolve-model and registry-normalize
- Warn on missing models.default during parse (tag Z2KP9NWQ)

packages/cli-workflow/src/commands/init/template.ts

@@ -13,19 +13,7 @@ import {
   templateTsconfigJson,
 } from "./templates.js";
 import type { CmdInitTemplateSuccess } from "./types.js";
-
-function validateWorkspaceSegment(name: string): Result<void, string> {
-  if (name.length === 0) {
-    return err("workspace name must not be empty");
-  }
-  if (name === "." || name === "..") {
-    return err("invalid workspace name");
-  }
-  if (name.includes("/") || name.includes("\\")) {
-    return err("workspace name must not contain path separators");
-  }
-  return ok(undefined);
-}
+import { validateWorkspaceSegment } from "./validate.js";
 
 function hasTemplatesWorkspaceGlob(workspaces: unknown): boolean {
   return Array.isArray(workspaces) && workspaces.includes("templates/*");

packages/cli-workflow/src/commands/init/validate.ts

@@ -0,0 +1,15 @@
+import { err, ok, type Result } from "@uncaged/workflow";
+
+/** Validates a single path segment for workspace / template names (no separators, not `.` / `..`). */
+export function validateWorkspaceSegment(name: string): Result<void, string> {
+  if (name.length === 0) {
+    return err("workspace name must not be empty");
+  }
+  if (name === "." || name === "..") {
+    return err("invalid workspace name");
+  }
+  if (name.includes("/") || name.includes("\\")) {
+    return err("workspace name must not contain path separators");
+  }
+  return ok(undefined);
+}

packages/cli-workflow/src/commands/init/workspace.ts

@@ -5,19 +5,7 @@ import { err, ok, type Result } from "@uncaged/workflow";
 
 import { pathExists } from "../../fs-utils.js";
 import type { CmdInitWorkspaceSuccess } from "./types.js";
-
-function validateWorkspaceSegment(name: string): Result<void, string> {
-  if (name.length === 0) {
-    return err("workspace name must not be empty");
-  }
-  if (name === "." || name === "..") {
-    return err("invalid workspace name");
-  }
-  if (name.includes("/") || name.includes("\\")) {
-    return err("workspace name must not contain path separators");
-  }
-  return ok(undefined);
-}
+import { validateWorkspaceSegment } from "./validate.js";
 
 function rootPackageJson(workspaceName: string): string {
   return `${JSON.stringify(