fix(methods): add missing .slack CLI hooks to agents.sessions example

The agents.sessions example dir was missing the .slack/ scaffold that every
other method family has, so `slack run` would not work there. Copy the
standard config.json, hooks.json, and .gitignore from a sibling.

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>

Author: zimeg

methods/src/agents_sessions/.slack/.gitignore

@@ -0,0 +1,2 @@
+apps.dev.json
+cache/

methods/src/agents_sessions/.slack/config.json

@@ -0,0 +1,6 @@
+{
+  "manifest": {
+    "source": "local"
+  },
+  "project_id": "00000000-0000-0000-0000-000000000000"
+}

methods/src/agents_sessions/.slack/hooks.json

@@ -0,0 +1,5 @@
+{
+  "hooks": {
+    "get-hooks": "python3 -m slack_cli_hooks.hooks.get_hooks"
+  }
+}