chore(scripts): add scripts index and archive one-shot scripts (#4822)

chore(scripts): index scripts/ and archive 29 one-shot scripts

backlog#1153 infra-13. scripts/ had 80+ unlabelled top-level entries
mixing CI gates with finished one-shot issue-validation scripts.

- scripts/README.md — one index row per entry with status
  (ci-gate / dev-tool / archived), purpose, and wiring; subdirectories
  get one row each. run_scanner_benchmarks.sh is annotated
  "disposition owned by backlog perf-10" and deliberately untouched.
- git mv 29 confirmed-stale one-shot entries to scripts/archive/:
  11 issue-scoped validation/perf-capture scripts, the 5-script
  backlog#706 large-PUT breakdown family, the 4-file GET-optimization
  stress suite, 2 gt1g one-shots, and 7 other orphaned one-shots.
  Evidence: a whole-tree boundary-aware reference census showed zero
  references from CI/Makefiles/docs/code for every moved entry (or
  references only from other scripts inside the same archived set);
  re-run after the move shows zero dangling references.
- docs/testing/README.md links the index.

Moves only — no script content changed.

scripts/archive/test_policy.json

@@ -0,0 +1,59 @@
+{
+    "Version": "2012-10-17",
+    "Statement": [
+        {
+            "Effect": "Allow",
+            "Action": [
+                "s3:GetObject"
+            ],
+            "Resource": [
+                "arn:aws:s3:::dada/*"
+            ],
+            "Condition": {
+                "StringEquals": {
+                    "s3:ExistingObjectTag/security": "public"
+                }
+            }
+        },
+        {
+            "Effect": "Allow",
+            "Action": [
+                "s3:DeleteObjectTagging"
+            ],
+            "Resource": [
+                "arn:aws:s3:::dada/*"
+            ],
+            "Condition": {
+                "StringEquals": {
+                    "s3:ExistingObjectTag/security": "public"
+                }
+            }
+        },
+        {
+            "Effect": "Allow",
+            "Action": [
+                "s3:DeleteObject"
+            ],
+            "Resource": [
+                "arn:aws:s3:::dada/*"
+            ]
+        },
+        {
+            "Effect": "Allow",
+            "Action": [
+                "s3:PutObject"
+            ],
+            "Resource": [
+                "arn:aws:s3:::dada/*"
+            ],
+            "Condition": {
+                "ForAllValues:StringLike": {
+                    "s3:RequestObjectTagKeys": [
+                        "security",
+                        "virus"
+                    ]
+                }
+            }
+        }
+    ]
+}