Add platform_hints config so an admin can append to or replace Hermes'
built-in platform hint for a single messaging platform (WhatsApp, Slack,
Telegram, ...) without affecting other platforms. Enables enterprise
managed profiles to steer platform-aware skills (e.g. invoke a custom
table-formatting skill on WhatsApp where Markdown tables don't render)
while leaving Telegram/Slack/CLI behavior unchanged.
- hermes_cli/config.py: document platform_hints in DEFAULT_CONFIG
- agent/agent_init.py: load platform_hints -> agent._platform_hint_overrides
- agent/system_prompt.py: _resolve_platform_hint() applies append/replace
(replace wins; bare string = append shorthand); defensive on bad config
- tests: 16 cases covering append/replace/shorthand/isolation/malformed
Override only affects the platform-hint segment of the system prompt;
SOUL/context/memory tiers and general instructions are unchanged.