Restore recipe selection + Run Recipe on beta

[coder13]

Restores the legacy recipe workflow on the beta branch (select recipe + run), without bringing back the Recipe Editor UI.

• Reintroduces src/lib/recipes/* (steps + built-in recipes).
• Adds a RUN_RECIPE action + reducer that executes the recipe using wca-group-generators (groups/assignments).
• Adds Recipe dropdown + “Run Recipe” button on the round page action row.
• Persists selected recipe to round extension data (roundConfig.recipe.id).

Notes:

• Does not restore Recipe Editor dialogs/components (they were unused and had been breaking TS build).
• yarn check:type passes.