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

scripts/check-dev-env.sh

@@ -89,7 +89,7 @@ echo ""
 echo "=== Config ==="
 
 # Check workflow config exists
-CONFIG_DIR="${UWF_STORAGE_ROOT:-$HOME/.shazhou/united-workforce}"
+CONFIG_DIR="${UWF_HOME:-$HOME/.shazhou/united-workforce}"
 check "config.yaml exists" \
   "[ -f '$CONFIG_DIR/config.yaml' ]" \
   "Run: uwf setup"