docs: add getting-started, cli, configuration, and architecture sections

[himewel]

Summary

• Adds four new doc pages mirroring the q2google structure: Getting Started, CLI, Configuration, and Architecture
• Adds a quick-links card grid to docs/index.md so every section is reachable from the home page
• Upgrades mkdocs.yml with Mermaid support (pymdownx.superfences), admonitions, tabbed content, emoji, and richer mkdocstrings options
• Adds a CI auto-label job that tags PRs with conventional-commit-based labels

New pages

Page	Contents
getting-started.md	Install (PyPI / source / wheel), token setup, sync & async quick-start
cli.md	Full reference for search, info, pull — all flags and examples
configuration.md	GP_ACCESS_TOKEN env var, .env usage, tabbed browser retrieval guide
ARCHITECTURE.md	Flowchart, sequence diagram, and class diagram (all Mermaid)

Test plan

• mkdocs serve renders all new pages without errors
• Mermaid diagrams display correctly in the Architecture page
• Card grid renders on the Home page
• Tabbed browser instructions render on the Configuration page
• Admonition warnings render on the Configuration page

Made with Cursor