fix: use RFC 2119 keywords in review-strategy-matches-criteria-scope

Restructured the requirement to use SHOULD/MAY/MUST NOT explicitly, matching
the RFC 2119 style of the other requirements in this schema. The substantive
guidance is unchanged: individual is preferred when focus is on each file and
the reviewer is unlikely to need to see the other changed files (consulting
unchanged project files is explicitly allowed as MAY); matches_together is
preferred when changed files need to be looked at alongside each other; and
individual is a hard MUST NOT when any criterion is a property of the set of
changed files as a whole.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nhorton

src/deepwork/standard_schemas/job_yml/deepschema.yml

@@ -77,16 +77,18 @@ requirements:
     outside their scope.
 
   review-strategy-matches-criteria-scope: >
-    Choose the review `strategy` based on whether the criteria need to reason across the
-    other changed files in the same review set. Use `individual` when the focus is
-    heavily on each file itself and the reviewer is unlikely to need to look at the other
-    changed files in order to evaluate this one — the reviewer MAY still consult unchanged
-    project files for context (imports, references, related code, conventions), and that
-    does not disqualify `individual`. Use `matches_together` when the changed files are
-    likely to need to be looked at alongside each other during review — e.g., criteria
-    about coverage across the set, deduplication, consistency between the files, or any
-    property of the set as a whole. Picking `individual` for set-level criteria forces
-    each spawned reviewer to redo the full cross-file scan N times and multiplies latency
+    The review `strategy` SHOULD match whether the criteria need to reason across the
+    other changed files in the same review set. `strategy: individual` SHOULD be used
+    when the focus is on each file itself and the reviewer is unlikely to need to see
+    the other changed files in order to evaluate this one. A reviewer operating under
+    `individual` MAY consult unchanged project files for context (imports, references,
+    related code, conventions); such consultation does NOT require switching to
+    `matches_together`. `strategy: matches_together` SHOULD be used when the changed
+    files are likely to need to be looked at alongside each other during review.
+    `strategy: individual` MUST NOT be used when any criterion is a property of the
+    set of changed files as a whole (e.g., coverage across the set, deduplication of
+    the set, cross-file consistency, set-level minimality), because it forces each
+    spawned reviewer to redo the cross-file scan N times and multiplies latency
     without improving review quality.
 
   review-no-redundant-context: >