refactor: unify env vars (UWF_HOME, OCAS_HOME) + env only in CLI (#37)

Breaking changes:
- UWF_STORAGE_ROOT → UWF_HOME
- WORKFLOW_STORAGE_ROOT removed (no fallback)
- OCAS_DIR → OCAS_HOME (aligned with ocas CLI)

Library functions no longer read process.env:
- util-agent/storage.ts: resolveStorageRoot(override), getGlobalCasDir(override)
- agent-hermes: isResumeDisabled(flag) pure function, CLI reads env
- agent-claude-code: CLI reads CLAUDE_MODEL and passes to agent

Fixes #37

packages/cli/src/__tests__/current-role.test.ts

@@ -225,9 +225,9 @@ describe("currentRole field", () => {
     await mkdir(storageRoot, { recursive: true });
     await mkdir(casDir, { recursive: true });
 
-    // Set OCAS_DIR for this test
-    originalEnv = process.env.OCAS_DIR;
-    process.env.OCAS_DIR = casDir;
+    // Set OCAS_HOME for this test
+    originalEnv = process.env.OCAS_HOME;
+    process.env.OCAS_HOME = casDir;
   }
 
   async function teardown() {
@@ -236,9 +236,9 @@ describe("currentRole field", () => {
     }
     // Restore original environment
     if (originalEnv === undefined) {
-      delete process.env.OCAS_DIR;
+      delete process.env.OCAS_HOME;
     } else {
-      process.env.OCAS_DIR = originalEnv;
+      process.env.OCAS_HOME = originalEnv;
     }
   }