fix(github): resolve the apply an operator meant when a control command names none

[aparajon]

Why this matters

schemabot apply takes no apply ID, so operators reach for schemabot cancel -e <env> the same way. Every apply-scoped control command answers that with a usage line, sending them to schemabot status to copy back an identifier SchemaBot already has — on a PR whose only schema change in that environment is the one they obviously meant.

What it does

• Resolves a control command that names no apply from the PR itself: acted on when exactly one schema change in that environment could be meant, answered with the candidates when several could, and given the existing usage reply when none match.
• Guesses nothing. An ambiguous command cancels nothing and lists the identifiers so the operator names the one they mean.
• Counts stopped applies as candidates. Stopping leaves a schema change half-applied and cancel is how an operator finishes it, so the state cancel is most often issued against stays reachable.
• Keeps the usage reply for an unscoped command on an aggregate repo. Each participant holds its own slice of the PR's applies, so "exactly one here" is not "exactly one on this PR".
• Threads the resolved apply back to the caller, so the acknowledgement names the apply it acted on rather than a blank.

Applies to every apply-scoped control command, since they share one lifecycle and the ask is the same on each.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Improves the operator experience for apply-scoped control commands (e.g., schemabot cancel) when issued without an explicit apply ID by resolving the intended apply from the PR when unambiguous, and replying with a candidate list when ambiguous.

Changes:

• Added control-command apply inference (and ambiguous-candidate replies) for apply-scoped control commands missing an apply ID.
• Added a new “Control Command Ambiguous Apply ID” PR comment template and CLI preview output for it.
• Added integration tests covering cancel-without-apply-id behavior for both unambiguous and ambiguous PRs.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
TEMPLATES.md	Documents the new ambiguous-apply-ID control-command template output.
pkg/webhook/templates/issue_comment.go	Adds rendering for the ambiguous apply-ID reply (candidate list + usage).
pkg/webhook/control.go	Implements apply inference for missing apply IDs and threads the resolved apply ID downstream.
pkg/webhook/control_integration_test.go	Adds E2E-style integration tests for cancel-without-apply-id behavior.
pkg/cmd/internal/templates/preview_comment.go	Adds preview entry for the new ambiguous apply-ID control-command comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.