refactor(protocol,cli,agent): replace apiKeyEnv with apiKey (#528)

Breaking change: Store API keys directly in config.yaml instead of
environment variable names.

## Changes

### @uncaged/workflow-protocol
- Change ProviderConfig.apiKeyEnv: string → apiKey: string
- Update README to reflect new type

### @uncaged/workflow-util-agent
- extract.ts: Remove dotenv loading, use providerEntry.apiKey directly
- storage.ts: Update normalizeProviders to validate apiKey field
- Update error messages to reference apiKey instead of apiKeyEnv

### @uncaged/cli-workflow
- setup.ts: Write actual API key to config.yaml, not .env
- Remove apiKeyEnvName(), loadEnvFile(), saveEnvFile() functions
- Remove getEnvPath() function
- Update cmdSetup to not return envPath in result
- Update README to reflect config.yaml stores API keys
- Fix setup-validate.test.ts to not expect envPath in result

## Verification
- ✅ bun run build passes
- ✅ All tests pass (260/260 in cli-workflow, 55/55 in util-agent)
- ✅ bun run check passes (only pre-existing warnings)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/workflow-util-agent/src/extract.ts

@@ -1,8 +1,7 @@
 import { getSchema, validate } from "@uncaged/json-cas";
 
 import type { CasRef, ModelAlias, WorkflowConfig } from "@uncaged/workflow-protocol";
-import { config as loadDotenv } from "dotenv";
-import { createAgentStore, getEnvPath, resolveStorageRoot } from "./storage.js";
+import { createAgentStore, resolveStorageRoot } from "./storage.js";
 
 export type ResolvedLlmProvider = {
   baseUrl: string;
@@ -38,9 +37,9 @@ export function resolveModel(config: WorkflowConfig, alias: ModelAlias): Resolve
   if (providerEntry === undefined) {
     throw new Error(`unknown provider "${modelEntry.provider}" for model "${alias}"`);
   }
-  const apiKey = process.env[providerEntry.apiKeyEnv];
+  const apiKey = providerEntry.apiKey;
   if (apiKey === undefined || apiKey === "") {
-    throw new Error(`missing API key env var: ${providerEntry.apiKeyEnv}`);
+    throw new Error(`missing API key for provider: ${modelEntry.provider}`);
   }
   return {
     baseUrl: providerEntry.baseUrl,
@@ -130,7 +129,7 @@ export type ExtractResult = {
 
 /**
  * Call an OpenAI-compatible LLM to extract structured output matching outputSchema.
- * Loads config.yaml and .env from the workflow storage root.
+ * Loads config.yaml from the workflow storage root.
  */
 export async function extract(
   rawOutput: string,
@@ -138,7 +137,6 @@ export async function extract(
   config: WorkflowConfig,
 ): Promise<ExtractResult> {
   const storageRoot = resolveStorageRoot();
-  loadDotenv({ path: getEnvPath(storageRoot) });
 
   const { store } = await createAgentStore(storageRoot);
   const schema = getSchema(store, outputSchema);

packages/workflow-util-agent/src/storage.ts

@@ -84,11 +84,11 @@ function normalizeProviders(raw: unknown): Record<ProviderAlias, ProviderConfig>
       throw new Error(`config.providers.${name} must be a mapping`);
     }
     const baseUrl = entry.baseUrl;
-    const apiKeyEnv = entry.apiKeyEnv;
-    if (typeof baseUrl !== "string" || typeof apiKeyEnv !== "string") {
-      throw new Error(`config.providers.${name} requires baseUrl and apiKeyEnv`);
+    const apiKey = entry.apiKey;
+    if (typeof baseUrl !== "string" || typeof apiKey !== "string") {
+      throw new Error(`config.providers.${name} requires baseUrl and apiKey`);
     }
-    providers[name] = { baseUrl, apiKeyEnv };
+    providers[name] = { baseUrl, apiKey };
   }
   return providers;
 }