feat: field-move Drop (partial/nested/ptr), stmt/pat macros, Windows runtime

Sessions 70–74: partialMovedPaths + ptrAliases in bootstrap/selfhost CBE,
remaining drops after field moves, macro stmt/pat fragments, runtime_win.c
and MinGW hello CI, examples + drop-move smoke coverage, QUALITY_PLAN update.

bootstrap/sema.nim

@@ -1902,6 +1902,10 @@ proc checkExpr*(sema: var Sema, expr: Expr, scope: Scope): Type =
     # Should have been expanded before analyze; leftover is a compiler bug
     sema.emitError(expr.loc, "unexpanded macro call '" & expr.exprMacroName & "!'")
     return makeUnknown()
+  of ekMacroStmt, ekMacroPat:
+    # Expand-only wrappers; must not reach type-checking
+    sema.emitError(expr.loc, "internal: unexpanded macro stmt/pat fragment")
+    return makeUnknown()
   of ekClosure:
     let savedRetType = sema.currentRetType
     let savedClosureDepth = sema.closureDepth