Add a per-client TLS transport toggle controlled from the server, using the
presence of the client's trust-anchor certificate in the registry as the
single source of truth (no separate tls_enable flag).
- Client reports its TLS status via a new RES_TLS token (cert present -> 1)
appended to LOGIN_INFOR's reserved field.
- Server online list gains a "TLS" column after the permission column.
- The "experimental features" right-click menu gains "TLS传输" / "取消TLS"
with confirmation and a guard that prompts (instead of sending) when the
server has no TLS certificate ready.
- New COMMAND_TLS_ENABLE / COMMAND_TLS_DISABLE (166/167): the server pushes
its cert PEM into the client registry settings\tls_cert (enable) or deletes
it (disable). The client picks this up on next startup via the existing
ReadTrustAnchor logic, so the switch is non-live by design.
- Icons and en_US/zh_TW/de_DE translations for the new menu items.
Co-Authored-By: deepseek-v4-pro
