Paper length gate

Internal deterministic pre-compile readiness check. The JSON input contains a paper contract and the compact manuscript manifest. For full manuscripts the manifest must point to a non-empty .tex file inside the active workspace. Compact and repair packages retain an inline-LaTeX compatibility path.

This gate checks document structure, citation presence, and a language-aware minimum body scale that grows with TARGET_PAGES. Its report-only preflight is used solely to drive one bounded authoring repair; a second fail-closed run must pass before compilation. It does not claim that the requested number of pages was produced. compile_pdf remains authoritative and counts pages from the compiled PDF with pypdf.