feat: lifetime elision, tooling CI, registry, and LSP locals

Ship the QUALITY_PLAN stretch from ownership through ecosystem: C.1
lifetime elision (bootstrap + selfhost), bux fmt/test/doc CI hooks,
stdlib goldens, package registry (bux search/add), and LSP 0.4
position-sensitive locals with inferred let types. Full-tree format
pass plus Map/Set remove double-free fix.

examples/structs.bux

@@ -16,7 +16,7 @@ func Main() -> int {
     let p1: Point = Point { x: 10, y: 20 };
     let p2: Point = Point { x: 5, y: 15 };
     let sum: Point = AddPoints(p1, p2);
-    
+
     PrintLine("Point sum:");
     PrintLine("x = ");
     PrintInt(sum.x);
@@ -24,6 +24,6 @@ func Main() -> int {
     PrintLine("y = ");
     PrintInt(sum.y);
     PrintLine("");
-    
+
     return 0;
 }