♻️ Move script-header rationale into development/

branch.sh, finish.sh, release.sh, runner-image.sh and release-notes.sh
carried multi-paragraph 'how we got here / rejected' essays in comments. They
now live in the matching development/ category file, and each script keeps a
one-line pointer so the rationale is single-homed and cannot drift.

scripts/branch.sh

@@ -4,43 +4,13 @@ set -eu
 
 # Branch front-door. Run as `npm run create:branch -- <prefix>/<desc>`.
 #
-# How we got here (short): the branching model says every change starts from a
-# clean, current `main`, and the type-driven loop only produces trustworthy
-# results if the baseline was green *before* the first edit. Both facts were
-# prose. Prose rots silently — a rule nobody checks is a suggestion — so the
-# precondition became this script: it asserts, then branches, and the branch
-# only appears if the assertions passed. Cheap checks run first, `npm run test`
-# runs last: the expensive gate is not paid on a tree that was never eligible.
+# Asserts the branch preconditions — clean tree, no in-progress operation,
+# current `main`, green baseline — and only then creates the branch, so the
+# expensive `npm run test` is not paid on a tree that was never eligible.
 #
-# Rejected for the prefix name: `run:` / `perform:` (both mean only "do the
-# thing named after them", so every script in the repo would fit under them and
-# the taxonomy collapses); `git:` (names the tool, not the lifecycle moment, and
-# advertises passthrough aliases); `start:` (describes this half, not the
-# release); `cut:` (idiomatic for both, but it needs VCS slang to decode, and a
-# signpost that has to be explained is not one); `flow:` (overloaded in a library
-# about type-level matching); and the existing families — `check:*` is read-only
-# and aggregated by `check`, so CI would run a command that mutates repo state;
-# `fix:*`'s review surface is a file diff, not a branch; `maintain:*` is advisory
-# and explicitly never a gate.
-#
-# `create:` was kept because both members really do create something: a branch,
-# a release. It was added to both prefix lists in CONTRIBUTING.md in the same
-# commit as its first members, because a prefix missing from those lists is
-# invisible — which was the `use:` mistake this repo carried in backlog.tasks (since retired into `setup:`).
-# There is deliberately no bare `create` aggregator: "run all the workflows"
-# describes nothing anyone wants, and `publish:*` already sets the precedent for
-# a prefix without one.
-#
-# Also rejected here: reusing `pubv`'s preflight (release-shaped, third-party,
-# and it would make branch start pay a build + pack it has no use for). The
-# merge half was originally rejected too ("review the diff yourself" is
-# judgment), but it now has its own front door — `create:finish` — which owns
-# the merge-side preconditions and the post-merge `verify`, so the start half
-# does not have to carry that burden.
-#
-# Every refusal is non-mutating except the baseline test, which runs on `main`
-# after we switch there — so a red `main` restores the branch you started on
-# rather than stranding you on it.
+# Why the front door exists, the rejected prefix names, and the `create:`
+# decision: development/workflow.md § Branching model and § Script prefix
+# convention.
 
 BASE="main"
 PREFIXES="feature fix chore"