Add Weixin messaging platform integration

[white0dew]

Summary

• add a new Weixin gateway platform backed by a local Node bridge and QR login flow
• wire Weixin through gateway auth, status, toolsets, cron delivery, send-message tooling, and docs
• add Weixin CLI setup plus regressions for true connection state, re-pair behavior, and DM authorization

Testing

• python -m py_compile agent/prompt_builder.py cron/scheduler.py gateway/channel_directory.py gateway/config.py gateway/platforms/weixin.py gateway/run.py gateway/session.py hermes_cli/config.py hermes_cli/gateway.py hermes_cli/main.py hermes_cli/setup.py hermes_cli/skills_config.py hermes_cli/status.py hermes_cli/tools_config.py tests/gateway/test_allowlist_startup_check.py tests/gateway/test_config.py tests/gateway/test_unauthorized_dm_behavior.py tests/gateway/test_weixin_connect.py tests/hermes_cli/test_weixin_cli.py tests/test_toolsets.py tests/tools/test_local_env_blocklist.py tests/tools/test_send_message_tool.py tools/cronjob_tools.py tools/environments/local.py tools/send_message_tool.py toolsets.py
• node --check scripts/weixin-bridge/bridge.js
• pytest is not installed in this environment, so the new tests could not be executed here

[teknium1]

Merged via PR #8665 which synthesizes the best fixes from ~25 community PRs into a single consolidated change. Your contribution (Weixin messaging integration) was reviewed and informed the final implementation. Thank you @white0dew for your work on this!