Write the shared federation capstone lab

Part of the content gap. The federation capstone lab has no content.

content/shared/ contains only setup.md. The manifest declares shared.capstone as federation-lab — "spin up both Pinboard implementations and federate them", attemptable after either track's Advanced federation module — and both php-a-03 and ex-a-03 are flagged federation_capstone: true.

This is the point where the two tracks converge, so it is the payoff for the whole course structure.

Depends on

The advanced modules of both tracks, at least the federation ones.

Note

The manifest's capstone entry lists downloads pointing at federation starting-point repos (e.g. pinboard-php-federation). Those repos need to exist — check before writing instructions that reference them. Related: the pinboard-python scaffold repo does not exist yet either.

Done when

The lab is written, and every repo or download it references actually exists.

Start by reading content/shared/setup.md and the manifest entry for shared.capstone, then review the advanced federation modules in both tracks. Check that every federation starting-point repository named in the manifest downloads exists before referencing it. Done means the capstone lab is written and all repositories or downloads it references are available.