docs: add gitignored research/scratch for local working notes

Maintainers can keep uncommitted drafts under docs/research/scratch/; only .gitkeep is tracked. Documented in docs/README.md alongside tracked research/ evaluations.

Author: SutuSebastian

.gitignore

@@ -17,3 +17,7 @@ fixtures/qa/*.local.md
 fixtures/benchmark/*.local.json
 .agent-eval/
 .tmp/
+
+# Maintainer-local docs working notes (not committed; see docs/README.md § research/scratch)
+docs/research/scratch/**
+!docs/research/scratch/.gitkeep

docs/README.md

@@ -24,7 +24,7 @@ Each topic has exactly one canonical file. Other files cross-reference by relati
 | [roadmap.md](./roadmap.md)                    | Forward-looking [**Backlog**](./roadmap.md#backlog) and [**Non-goals**](./roadmap.md#non-goals-v1) (not a `src/` inventory).                                                                                                                                                                                                                                                                                                                                                                                                                             |
 | [plans/](./plans/)                            | One `<feature-name>.md` per in-flight plan. Created on demand — don't add the `-plan` suffix; the folder provides context. See folder contents for the current in-flight set; avoid maintaining a duplicate inline list.                                                                                                                                                                                                                                                                                                                                 |
 | [audits/](./audits/)                          | Targeted architecture / performance / lifecycle audits. None open.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
-| [research/](./research/)                      | Dated snapshot notes for **open** evaluations. Closed adopted notes delete after lift; rejected notes keep a one-line status header only.                                                                                                                                                                                                                                                                                                                                                                                                                |
+| [research/](./research/)                      | Dated snapshot notes for **open** evaluations (tracked). Closed adopted notes delete after lift; rejected notes keep a one-line status header only. **Local working notes:** [`research/scratch/`](./research/scratch/) — gitignored maintainer drafts; not committed; delete when content has landed elsewhere or is no longer needed.                                                                                                                                                                                                                  |
 
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