docs: codify PM-level, short PR descriptions in the org PR template

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,13 +1,26 @@
-Please include a summary of the changes. **What** has changed and **why**?.
+<!--
+Write for the project manager deciding whether this change is needed — not for
+a code reviewer (CodeRabbit and CI validate correctness). Keep it SHORT:
+1–3 plain-language sentences per section. No code detail — no file paths,
+symbols, snippets, or test/lint output. The change type lives in the PR title
+(Conventional Commits), not here.
+-->
 
-Fixes [url OR #issue]
+## Why
 
-## Type of change
+<!-- The problem this solves and why it matters. -->
 
-Select the appropriate options and delete the rest:
+## What
 
-- [ ] 🧹 Refactor
-- [ ] 🪲 Bug fix
-- [ ] 🚀 New feature
-- [ ] ⛓️‍💥 Breaking change
-- [ ] 📚 Documentation update
+<!-- What the change does, at outcome level. -->
+
+Fixes #
+
+<!--
+Only if applicable — one line each, delete the rest:
+
+⚠️ Merge order: land #N first, or <what breaks>.
+💥 Breaking change: <what breaks, for whom>.
+📦 New dependency: <name> — <why>.
+👉 After merge/promotion: <action the maintainer must take>.
+-->