feat: add architecture and file size checks to review loops

Spec reviewer now checks for unit decomposition with clear boundaries.
Plan reviewer now checks file structure and whether files will grow
too large to reason about.

skills/brainstorming/spec-document-reviewer-prompt.md

@@ -23,6 +23,7 @@ Task tool (general-purpose):
     | Consistency | Internal contradictions, conflicting requirements |
     | Clarity | Ambiguous requirements |
     | YAGNI | Unrequested features, over-engineering |
+    | Architecture | Units with clear boundaries, well-defined interfaces, independently understandable and testable |
 
     ## CRITICAL
 
@@ -30,6 +31,7 @@ Task tool (general-purpose):
     - Any TODO markers or placeholder text
     - Sections saying "to be defined later" or "will spec when X is done"
     - Sections noticeably less detailed than others
+    - Units that lack clear boundaries or interfaces — can you understand what each unit does without reading its internals?
 
     ## Output Format