chore: replace the org PR template with a merge brief

pull_request_template.md

@@ -1,31 +1,42 @@
-<!-- Thanks for your Pull Request, please read the contributing guidelines before submitting. -->
-
-<!-- Use the snippet below for chained PRs
-> [!CAUTION]
-> Chained to #PR
+<!--
+Merge brief. Write for the person who approves the merge, not for someone reading the code.
+Every line must help them decide to merge, or know what to watch after the merge.
+If a reviewer can learn it from the diff, cut it. There is no How section.
+Delete every section that has nothing real to say. A trivial PR is the headline plus the slot line.
+Budget: about 150 words for low risk, 250 for medium, and 400 for high. At most 3 bullets per section.
 -->
 
-## Motivation
+<!-- Headline: 1 to 3 sentences. What the system does after the merge, where its output goes, and why now. Link the issue. In a stack, say which part this is. -->
 
-<!--
-Explain the context and why you're making that change. What is the problem
-you're trying to solve? In some cases there is not a problem and this can be
-thought of as being the motivation for your change.
--->
+**Live effect:** <!-- none, or what changes for users, money, services, or alerts --> · **Risk:** <!-- low, medium, or high, with the triggers in parentheses: money path, keys or IAM, production config or infrastructure, stored data, hard to undo --> · **Ships:** <!-- on merge, next release, or after a manual step --> · **Blocks:** <!-- PRs that must merge after this one, or delete this slot -->
 
-## Solution
+## Needs your call
 
-<!--
-Summarize the solution and provide any necessary context needed to understand
-the code change.
--->
+<!-- Only if you need a human decision. @mention the person who must answer. -->
+
+-
+
+## Decisions
+
+<!-- Only choices a teammate could dispute. "X, not Y, because Z." Link each to its lines in the diff. -->
+
+-
+
+## Risks
+
+<!-- What can go wrong, how bad it is, and what limits it or which issue follows up. -->
+
+-
+
+## Proof
+
+<!-- The strongest evidence that it works: the test that reproduces the bug, a staging check, the plan summary, a screenshot. Not a list of every test. -->
+
+-
+- **Not verified:** <!-- what nobody checked, human or agent -->
 
-## Checks
+## Rollout
 
-<!-- It's important you've done these, or your PR will not be considered for review -->
-By submitting this for review, I'm confirming I've done the following:
+<!-- Only if live behavior changes or a manual step is needed. Give each step the signal to check. The last step is the rollback. -->
 
-- [ ] added comprehensive test coverage for any changes in logic
-- [ ] made this PR as small as possible
-- [ ] linked any relevant issues or PRs
-- [ ] included screenshots (if this involves a change to a front-end/dashboard)
+1.