revert(acp): remove claude-login from auth method map

The previous fix added claude-login to _AUTH_METHOD_ENV_MAP, but
Claude Code ACP doesn't support this authentication flow via
conn.authenticate(). Instead, Claude Code uses bypassPermissions
mode which works without explicit authentication.

Reverting to the previous behavior where claude-login triggers
a warning but falls back to bypassPermissions mode.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: simonrosenberg

openhands-sdk/openhands/sdk/agent/acp_agent.py

@@ -118,8 +118,9 @@ def _make_dummy_llm() -> LLM:
 # ACP auth method ID → environment variable that supplies the credential.
 # When the server reports auth_methods, we pick the first method whose
 # required env var is set.
+# Note: claude-login is intentionally NOT included because Claude Code ACP
+# uses bypassPermissions mode instead of API key authentication.
 _AUTH_METHOD_ENV_MAP: dict[str, str] = {
-    "claude-login": "ANTHROPIC_API_KEY",
     "codex-api-key": "CODEX_API_KEY",
     "openai-api-key": "OPENAI_API_KEY",
 }