Submitted corpus proposals

This is where a submitted corpus proposal lives (research item E5). Drop one YAML file per species here and open a PR:

uv run sprout propose template > proposals/my-plant.yaml
uv run sprout propose check proposals/my-plant.yaml   # review just this one
uv run sprout propose check                           # what CI runs: every proposal

sprout propose check with no arguments is the merge-blocking gate (make propose-check, and the propose-check step of the eval-a11y CI job). It does not look only here: it walks the repository and reviews every file with the shape of a proposal, wherever it was filed, and reports a proposal outside proposals/ or examples/corpus-proposal/ as an error rather than skipping it. Discovering no proposals at all is a hard failure, so the gate cannot quietly pass by reviewing nothing.

The worked example, the full rule table, and what each of the three statuses means are in examples/corpus-proposal/README.md. Nothing here is ever written into corpus/ automatically — a proposal is reviewed, then merged by a human.