feat: Implement Mattermost sync functionality and enhance workspace context management

.gitignore

@@ -0,0 +1,19 @@
+.DS_Store
+
+# Python caches
+__pycache__/
+*.py[cod]
+
+# Local virtual environments
+.venv/
+
+# Mattermost raw inbox artifacts
+ai/inbox/mattermost-latest.md
+ai/inbox/mattermost-*.md
+ai/inbox/mattermost-status.json
+
+# Workspace-local Mattermost runtime artifacts
+scripts/mattermost/.env
+scripts/mattermost/.venv/
+scripts/mattermost/generated/*
+!scripts/mattermost/generated/.gitkeep