Splitting ref and sha into two fields correctly for the intake form (#1788)

* Splitting ref and sha into two fields correctly for the intake form

* Enforce 40-character commit SHA in validateImmutableRef

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

* Add backward compatibility for legacy checklist text and field title

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

* Avoid unnecessary array spread when iterating checklist equivalents

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

.github/ISSUE_TEMPLATE/external-plugin.yml

@@ -14,7 +14,7 @@ body:
         Before you continue:
         - Public submissions are **GitHub-only** in v1.
         - The plugin must live in a **public GitHub repository**.
-        - Use an **immutable ref** for review: a release tag or full 40-character commit SHA.
+        - Provide an immutable **ref**, **sha**, or both for review.
         - Do **not** open a PR that edits `plugins/external.json` directly.
   - type: input
     id: plugin-name
@@ -51,11 +51,19 @@ body:
   - type: input
     id: immutable-ref
     attributes:
-      label: Immutable ref to review
-      description: Release tag or full 40-character commit SHA.
-      placeholder: refs/tags/v1.2.3 or 0123456789abcdef0123456789abcdef01234567
+      label: Ref to review
+      description: Optional release tag or tag ref. Submit this, a commit SHA, or both.
+      placeholder: v1.2.3
     validations:
-      required: true
+      required: false
+  - type: input
+    id: immutable-sha
+    attributes:
+      label: Commit SHA to review
+      description: Optional full 40-character commit SHA. Submit this, a ref, or both.
+      placeholder: 0123456789abcdef0123456789abcdef01234567
+    validations:
+      required: false
   - type: input
     id: version
     attributes:
@@ -119,7 +127,7 @@ body:
       options:
         - label: The plugin lives in a public GitHub repository.
           required: true
-        - label: The ref I provided is an immutable release tag or full 40-character commit SHA, not a branch.
+        - label: The ref and/or sha I provided is immutable (release tag and/or full 40-character commit SHA), not a branch.
           required: true
         - label: This submission follows this repository's contribution, security, and responsible AI policies.
           required: true