* fix: Anthropic OAuth compatibility — Claude Code identity fingerprinting
Anthropic routes OAuth/subscription requests based on Claude Code's
identity markers. Without them, requests get intermittent 500 errors
(~25% failure rate observed). This matches what pi-ai (clawdbot) and
OpenCode both implement for OAuth compatibility.
Changes (OAuth tokens only — API key users unaffected):
1. Headers: user-agent 'claude-cli/2.1.2 (external, cli)' + x-app 'cli'
2. System prompt: prepend 'You are Claude Code, Anthropic's official CLI'
3. System prompt sanitization: replace Hermes/Nous references
4. Tool names: prefix with 'mcp_' (Claude Code convention for non-native tools)
5. Tool name stripping: remove 'mcp_' prefix from response tool calls
Before: 9/12 OK, 1 hard fail, 4 needed retries (~25% error rate)
After: 16/16 OK, 0 failures, 0 retries (0% error rate)
* fix: auto-detect DBUS_SESSION_BUS_ADDRESS for systemctl --user on headless servers
On SSH sessions to headless servers, DBUS_SESSION_BUS_ADDRESS and
XDG_RUNTIME_DIR may not be set even when the user's systemd instance
is running via linger. This causes 'systemctl --user' to fail with
'Failed to connect to bus: No medium found', breaking gateway
restart/start/stop as a service and falling back to foreground mode.
Add _ensure_user_systemd_env() that detects the standard D-Bus socket
at /run/user/<UID>/bus and sets the env vars before any systemctl --user
call. Called from _systemctl_cmd() so all existing call sites benefit
automatically with zero changes.
Fixes: gateway restart falling back to foreground on headless servers
* fix: show linger guidance when gateway restart fails during update and gateway restart
When systemctl --user restart fails during 'hermes update' or
'hermes gateway restart', check linger status and tell the user
exactly what to run (sudo -S -p '' loginctl enable-linger) instead of
silently falling back to foreground mode.
Also applies _ensure_user_systemd_env() to the raw systemctl calls
in cmd_update so they work properly on SSH sessions where D-Bus
env vars are missing.