feat(teams-pipeline): add plugin runtime and operator cli

Third slice of the Microsoft Teams meeting pipeline stack, salvaged
onto current main. Adds the standalone teams_pipeline plugin that
consumes Graph change notifications from the webhook listener,
resolves meeting artifacts (transcript first, recording + STT fallback
later), persists job state in a durable store, and exposes an operator
CLI for inspection, replay, subscription management, and validation.

Design choices follow maintainer review feedback on PR #19815:

- Standalone plugin rather than bolted-on core surface
  (plugins/teams_pipeline/, kind: standalone in plugin.yaml).
- Zero new model tools. The agent drives the pipeline by invoking
  the operator CLI via the terminal tool, guided by the skill that
  ships with a follow-up PR.
- Reuses the existing msgraph_webhook gateway platform for Graph
  ingress. Pipeline runtime is wired in via bind_gateway_runtime and
  gated on plugins.enabled so gateways that don't run the plugin
  boot cleanly.

Additions:

- plugins/teams_pipeline/: runtime (gateway wiring + config builder),
  pipeline core, durable SQLite store, subscription maintenance
  helpers, Graph artifact resolution, operator CLI (list, show,
  run/replay, fetch dry-run, subscriptions list, subscribe,
  renew-subscription, delete-subscription, maintain-subscriptions,
  token-health, validate).
- hermes_cli/main.py: second-pass plugin CLI discovery so any
  standalone plugin registered via ctx.register_cli_command()
  outside the memory-plugin convention path gets its subcommand
  wired into argparse without touching core.
- gateway/run.py: _teams_pipeline_plugin_enabled() config gate,
  _wire_teams_pipeline_runtime() binding after adapter setup, and
  the two runner attributes used by the runtime.

Credit to @dlkakbs for the entire plugin implementation.

hermes_cli/main.py

@@ -10052,7 +10052,9 @@ Examples:
     # =========================================================================
     try:
         from plugins.memory import discover_plugin_cli_commands
+        from hermes_cli.plugins import discover_plugins, get_plugin_manager
 
+        seen_plugin_commands = set()
         for cmd_info in discover_plugin_cli_commands():
             plugin_parser = subparsers.add_parser(
                 cmd_info["name"],
@@ -10061,6 +10063,23 @@ Examples:
                 formatter_class=__import__("argparse").RawDescriptionHelpFormatter,
             )
             cmd_info["setup_fn"](plugin_parser)
+            if cmd_info.get("handler_fn") is not None:
+                plugin_parser.set_defaults(func=cmd_info["handler_fn"])
+            seen_plugin_commands.add(cmd_info["name"])
+
+        discover_plugins()
+        for cmd_info in get_plugin_manager()._cli_commands.values():
+            if cmd_info["name"] in seen_plugin_commands:
+                continue
+            plugin_parser = subparsers.add_parser(
+                cmd_info["name"],
+                help=cmd_info["help"],
+                description=cmd_info.get("description", ""),
+                formatter_class=__import__("argparse").RawDescriptionHelpFormatter,
+            )
+            cmd_info["setup_fn"](plugin_parser)
+            if cmd_info.get("handler_fn") is not None:
+                plugin_parser.set_defaults(func=cmd_info["handler_fn"])
     except Exception as _exc:
         logging.getLogger(__name__).debug("Plugin CLI discovery failed: %s", _exc)