ci(scripts): add s3s footprint ratchet ahead of s3gate migration (#5739)

Freeze the direct s3s dependency surface with a lower-only ratchet so it
cannot grow while the s3gate/gateway migration shrinks it
(rustfs/backlog#1677 review finding F1; acceptance criteria in
rustfs/backlog#1733). Baselines verified on 2026-08-05: 236 files
importing s3s, 1686 s3_error! invocation lines. Wired into make
pre-commit / pre-pr / dev-check and the Quick Checks job in ci.yml and
its ci-docs-only.yml mirror.

.github/workflows/ci-docs-only.yml

@@ -114,6 +114,9 @@ jobs:
       - name: Check body-cache whitelist guard
         run: ./scripts/check_body_cache_whitelist.sh
 
+      - name: Check s3s footprint ratchet
+        run: ./scripts/check_s3s_footprint.sh
+
       - name: Check no planning docs committed
         run: ./scripts/check_no_planning_docs.sh
 

.github/workflows/ci.yml

@@ -149,6 +149,9 @@ jobs:
       - name: Check body-cache whitelist guard
         run: ./scripts/check_body_cache_whitelist.sh
 
+      - name: Check s3s footprint ratchet
+        run: ./scripts/check_s3s_footprint.sh
+
       - name: Check no planning docs committed
         run: ./scripts/check_no_planning_docs.sh