feat(docs): Populate Developer Portal with comprehensive documentation framework (#35217)

Co-authored-by: Claude <noreply@anthropic.com>

docs/developer_portal/capabilities/common-capabilities.md

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+---
+title: Common Plugin Capabilities
+sidebar_position: 2
+---
+
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+
+# Common Plugin Capabilities
+
+🚧 **Coming Soon** 🚧
+
+Explore the shared functionality and common patterns available to all Superset plugins.
+
+## Topics to be covered:
+
+- Plugin lifecycle hooks (initialization, activation, deactivation)
+- Accessing Superset's core services and APIs
+- State management and data persistence
+- Event handling and plugin communication
+- Internationalization (i18n) support
+- Error handling and logging
+- Plugin configuration management
+- Accessing user context and permissions
+- Working with datasets and queries
+- Plugin metadata and manifests
+
+## Core Services Available
+
+- **API Client** - HTTP client for backend communication
+- **State Store** - Redux store access
+- **Theme Provider** - Access to current theme settings
+- **User Context** - Current user information and permissions
+- **Dataset Service** - Working with data sources
+- **Chart Service** - Chart rendering utilities
+
+---
+
+*This documentation is under active development. Check back soon for updates!*