Breaking: removes fetch-depth, filter, sparse-checkout, sparse-checkout-cone-mode
inputs. Composite always populates full history + blob:none so every caller
for the same SHA gets the same tarball. Cache key simplifies to repo-<sha>.
Rationale: every sparse callsite in cula-platform runs downstream of a
full-tree-populating job (find_affected). Full-tree restore (~3-5s) is
faster than sparse clone (~10-20s). One cache entry per SHA, no
fragmentation, no races on conflicting tarball contents.
If someone needs a sparse checkout outside the cache, use raw actions/checkout.
Required when sparse-checkout patterns include files (not just dirs) —
lint-github-docs uses cone-mode=false to pin package.json, pnpm-lock.yaml
etc. Without the passthrough actions/checkout treats files as dirs.
Adds sparse-checkout input. When set, the composite skips GCS restore
and save entirely and falls through to a plain actions/checkout. This
keeps the full-tree cache uncontaminated by sparse subsets (which
would break subsequent full-tree reads on cache hit).
First-step-capable checkout wrapper: uses Cula-Technologies/cache/restore
to pull a tarball of the repo keyed on SHA, falls back to actions/checkout
on miss then saves. Meant to be the first step of a job — avoids the
local-composite chicken-and-egg.
