Add a status checklist as the authoritative plan-progress record

Completion status previously lived only in my in-session TodoWrite list
(ephemeral, doesn't survive the session) or had to be inferred from which
steps had an entry in the execution log. Neither is a durable, explicit
answer to "what's left."

Adds a markdown checklist at the top of each plans-executions file, one
line per plan step, checked in the same commit as that step's entry. A
new session resuming this plan can read the file alone and know exactly
where to pick up.

Co-Authored-By: Claude <noreply@anthropic.com>

docs/plans-executions/2026-08-07-1747-proxy-operator.md

@@ -2,6 +2,22 @@
 
 Pairs with [docs/plans/2026-08-07-1747-proxy-operator.md](../plans/2026-08-07-1747-proxy-operator.md).
 
+## Status
+
+- [x] Step 0 — Branch and scaffold
+- [ ] Step 1 — API types (`api/v1alpha1/proxy_types.go`)
+- [ ] Step 2 — Provider contract (`internal/provider/`)
+- [ ] Step 3 — Mock provider (`internal/provider/mock/`)
+- [ ] Step 4 — Reconciler (`internal/controller/`)
+- [ ] Step 5 — Health engine (`internal/health/`)
+- [ ] Step 6 — Lease store (`internal/lease/`)
+- [ ] Step 7 — Discovery API (`internal/discovery/`)
+- [ ] Step 8 — GCP provider (`internal/provider/gcp/`)
+- [ ] Step 9 — Orphan GC + metrics
+- [ ] Step 10 — Wiring, config, docs
+- [ ] Step 11 — Tests
+- [ ] Verification (vet/test/kind e2e) + commit, push, open MR
+
 ## Step 0 — Branch and scaffold
 
 Branched off the unborn `main`: