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>

plugins/platforms/teams/plugin.yaml

@@ -0,0 +1,13 @@
+name: teams-platform
+kind: platform
+version: 1.0.0
+description: >
+  Microsoft Teams gateway adapter for Hermes Agent.
+  Connects to Microsoft Teams via the Bot Framework and relays messages
+  between Teams chats (personal DMs, group chats, channel posts) and
+  the Hermes agent. Supports Adaptive Card approval prompts.
+author: Aamir Jawaid
+requires_env:
+  - TEAMS_CLIENT_ID
+  - TEAMS_CLIENT_SECRET
+  - TEAMS_TENANT_ID