feat(teams): add Microsoft Teams platform adapter as a plugin

Hello! I am the maintainer of the microsoft-teams-apps Python SDK and
I built this Teams adapter to integrate Microsoft Teams into Hermes.

Adds a `plugins/platforms/teams` platform plugin using the new
PlatformRegistry system from #17751. The adapter self-registers via
`register(ctx)` — no hardcoding in run.py, toolsets.py, or any
other core file.

Key features:
- Supports personal DMs, group chats, and channel posts
- Adaptive Card approval prompts with in-place button replacement
  (Allow Once / Allow Session / Always Allow / Deny)
- aiohttp webhook server bridged from the Teams SDK to avoid
  the fastapi/uvicorn dependency
- ConversationReference caching for correct proactive sends in
  non-DM chats
- `interactive_setup()` for `hermes gateway setup` integration
- `platform_hint` for LLM context (Teams markdown subset)
- 34 tests covering adapter init, send, message handling, and
  plugin registration

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cli-config.yaml.example

@@ -570,7 +570,7 @@ agent:
 #   - A preset like "hermes-cli" or "hermes-telegram" (curated tool set)
 #   - A list of individual toolsets to compose your own (see list below)
 #
-# Supported platform keys: cli, telegram, discord, whatsapp, slack, qqbot
+# Supported platform keys: cli, telegram, discord, whatsapp, slack, qqbot, teams
 #
 # Examples:
 #
@@ -600,6 +600,7 @@ agent:
 #   signal:        hermes-signal         (same as telegram)
 #   homeassistant: hermes-homeassistant  (same as telegram)
 #   qqbot:            hermes-qqbot            (same as telegram)
+#   teams:            hermes-teams            (same as telegram)
 #
 platform_toolsets:
   cli: [hermes-cli]
@@ -611,6 +612,7 @@ platform_toolsets:
   homeassistant: [hermes-homeassistant]
   qqbot: [hermes-qqbot]
   yuanbao: [hermes-yuanbao]
+  teams: [hermes-teams]
 
 # =============================================================================
 # Gateway Platform Settings