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/strings2.bux

@@ -65,10 +65,10 @@ func Main() -> int {
     StringBuilder_Append(&sb, "World");
     StringBuilder_Append(&sb, "! #");
     StringBuilder_AppendInt(&sb, 42);
-    
+
     Print("StringBuilder: ");
     PrintLine(StringBuilder_Build(&sb));
     StringBuilder_Free(&sb);
 
     return 0;
-}
+}