Delete the dead CLI template-renderer shim and its source-text guard

[tobyhede]

Parent

#799. Design record: .scratch/render-execution-unit/spec.md.

What to build

Delete the CLI's template-renderer shim. It has zero production importers — the execution loop imports the expanders straight from core — and its only remaining consumers are test files, one of which is a source-text regex asserting that the shim is a wrapper.

That regex is the clearest instance of the pattern that motivated the parent review: a source-text test defending a module that nothing uses.

Acceptance criteria

• The shim is deleted.
• Its test consumers point at core directly, or are deleted where they only tested the shim's existence.
• The source-text regex asserting the wrapper shape is removed.
• pnpm run verify green.

Blocked by

• Introduce the core entry seam; the execution loop becomes its only caller #819