Introduce a language selection command backed by a supported-language
table and per-language response instructions. The chosen code is stored
as `preferred_language` in the user profile and injected into the system
prompt so replies follow the selected language, with an `auto` option
for detection.
Also refreshes the agent and user profile timestamps and appends the
latest conversation context entries.
Extend the /help message so users can discover the full user manual
with examples and tips via /manual, and view system information,
version, author, and license via /about.
Also includes the generated conversation context snapshot for
2026-10-26 and the recompiled agent bytecode.