Epic: The Starlark authoring surface #445

Specs: 3.2-projected-provider-api.md ·
star-extensions.md
Plans: star-gen-receiver.md ·
star-provider-migration.md ·
star-source-analysis.md ·
consolidate-starlark-runtime.md ·
variadic-starlark-args.md ·
move-star-to-devlore-cli.md ·
devlore-command-tree.md

Everything an author touches: how provider methods project into Starlark, how extensions declare commands
and bind functions, how arguments convert, and the star CLI that runs it all.