refactor: simplify PR assignment check workflow prompt

Make the workflow logic clearer by listing the two failure conditions upfront:
1. PR doesn't reference any issue
2. PR references an issue where author is not assigned

This makes it easier to understand when PRs will be closed.

Author: maxprilutskiy

.github/workflows/pr-assignment-check.yml

@@ -30,16 +30,14 @@ jobs:
           prompt: |
             EXEMPT USERS: @maxprilutskiy, @vrcprl, @davidturnbull, @monicabe, @sumitsaurabh927, @AleksandrSl (skip all checks if PR author is one of these)
 
-            Check if this PR references any issues (via "Closes #123", "Fixes #456", etc.).
+            Close this PR if:
+            1. It doesn't reference any issue (no "Closes #123", "Fixes #456", etc.)
+            2. OR it references an issue where the PR author is NOT assigned
 
-            For each referenced issue:
-            1. Check if the issue has assignees
-            2. If yes, check if the PR author is one of the assignees
-            3. If the PR author is NOT an assignee, close this PR with a brief, friendly comment (2-3 sentences, no emojis) explaining:
-               - The issue was already assigned to someone else
-               - They should wait to be assigned before submitting PRs
-               - Encourage them to find other unassigned issues
+            When closing, leave a brief, friendly comment (2-3 sentences, no emojis) explaining:
+            - They need to reference an assigned issue or get assigned first
+            - They should find unassigned issues to work on
 
-            If no issues referenced or PR author is properly assigned, do nothing.
+            Otherwise, do nothing.
           claude_args: |
             --allowedTools "Bash,Read,Grep,Glob"