♻️ Drop the last duplicated prose from development/

The GitHub Flow description and the type-first enforcement sentence still
appeared in both CONTRIBUTING.md and development/. development/ now carries only
the context and rationale that is not in CONTRIBUTING.md.

development/workflow.md

@@ -7,15 +7,12 @@ are shaped the way they are.
 
 ## Branching model
 
-**GitHub Flow (single-developer).** Every change — feature, fix, refactor —
-branches off `main` and is merged back via a local commit. There is no pull
-request workflow on Gitea yet: collaborative review through the Gitea UI is not
-in place, so Gitea is the lab. When something is tested and ready for
-production it will be promoted to GitHub.
-
 The contributor-facing steps are in
-[CONTRIBUTING.md § Branching model](../CONTRIBUTING.md#branching-model); what
-follows is why the front doors exist and what was rejected.
+[CONTRIBUTING.md § Branching model](../CONTRIBUTING.md#branching-model). Two
+bits of context behind the model: collaborative review through the Gitea UI is
+not in place, so Gitea is the lab; and the project will be promoted to GitHub
+once it is tested and ready for production. What follows is why the front doors
+exist and what was rejected.
 
 #### Decision (2026-09)