feat(api): project coordination report — missing sections, broken refs, unmapped elements

[thewrz]

Context

#84's missing-required-sections preflight is one signal of a broader coordination surface. Spec writers need a single errors-and-omissions view per project.

Scope

Create:

• GET /projects/:id/coordination-report + MCP tool aggregating typed findings:
  1. Missing required sections (feat(revit): family-category → required MasterFormat sections registry + project preflight #84 core)
  2. Broken cross-references (existing getBrokenRefs query)
  3. Unmapped Revit elements / specs without model backing (feat(api): revit link inventory — element↔spec mapping read model #103)
  4. Parse warnings + inference conflicts (feat(parser): surface DOCX inference conflicts via get_paragraph MCP tool #56)
  5. Keynotes whose target section left the TOC (ADR-016)

Acceptance

• Report fixture with one defect of each class → five typed findings
• Each finding carries enough context to act (section, ref, element id, or keynote code)

Blocked by

#84, #103

Out of scope

Auto-remediation; UI rendering of the report (Phase 5).