feat(platforms): implement Platform Registry as single source of truth

[mischadiehm]

Overview

Implement a centralized Platform Registry that serves as the single source of truth for all platform metadata. Previously, platform information was scattered across 10+ files. Now adding a new platform requires updating only one file.

Core Implementation

• registry.py: Pydantic models (PlatformStatus, PlatformCapabilities, PlatformInfo)
• PLATFORM_REGISTRY: 10 platforms (3 implemented, 3 sequences_only, 4 planned)
• Deleted 3 redundant constants.py files - registry is now the single source
• Updated factory.py and operations classes to query registry
• Updated config.py to use registry for device type validation

CLI Commands

nw platforms list                          # List all platforms
nw platforms list --status implemented     # Filter by status
nw platforms list --vendor cisco           # Filter by vendor
nw platforms list --capability config_backup  # Filter by capability
nw platforms info mikrotik_routeros        # Detailed platform info

Python API

from network_toolkit.api import list_platforms, get_platform_details, PlatformListOptions

# List all platforms
result = list_platforms()

# Filter by status
result = list_platforms(PlatformListOptions(status="implemented"))

# Get details for a specific platform
details = get_platform_details("mikrotik_routeros")

Auto-Generated Documentation

• scripts/generate_platform_docs.py generates docs from registry
• Generated files in docs/.generated/ are included via MkDocs snippets
• Platform tables stay synchronized with code automatically

New Documentation

• docs/adding-platforms.md: 800-line contributor guide with examples and checklists
• Updated docs/multi-vendor-support.md with CLI examples
• Updated docs/vendors/index.md with auto-generated vendor list

Testing

• 49 registry tests (models, queries, validation, integrity)
• 24 CLI tests (list filters, info, error handling)
• 30 API tests (list_platforms, get_platform_details, filtering)
• Total: 103 new platform-related tests, all passing

Squash commit message

feat(platforms): implement Platform Registry as single source of truth

Replace scattered platform metadata with centralized registry system.
Adding new platforms now requires updating only one file instead of 10+.

- Add registry.py with Pydantic models for platform metadata
- Add PLATFORM_REGISTRY with 10 platforms (MikroTik, Cisco, Arista, etc.)
- Add CLI commands: nw platforms list/info with filtering options
- Add Python API: list_platforms(), get_platform_details()
- Add auto-generation script for documentation from registry
- Add docs/adding-platforms.md contributor guide
- Add 103 tests for registry, CLI, and API
- Delete redundant constants.py files

Test plan

• All 1087 tests pass
• Pre-commit checks pass
• MkDocs builds without warnings in strict mode
• CLI commands work correctly with all filter options
• Python API exports are accessible from network_toolkit.api