Merge origin/dev into engram-tiered-storage

Resolve 3 conflicts:
- lang/el-compiler/runtime/el_runtime.c: keep deletion (deprecated runtime fork;
  single-source-of-truth is lang/runtime/, enforced by scripts/check-single-runtime.sh).
- lang/releases/v1.0.0-20260501/el_runtime.h: keep deletion (releases/ is a generated
  artifact folder, not a source path; a release is a git tag, not a folder).
- lang/runtime/el_platform_win.h: union of dev's Windows port (#80: setsockopt optval
  wrapper + curl-less libcurl stubs) and our fsync(->_commit) shim needed by engram_store WAL.

Nothing in dev's build consumes the deprecated fork or releases/ folder.

lang/runtime/el_seed.c

@@ -1072,6 +1072,7 @@ el_val_t __engram_save(el_val_t path)                       { return engram_save
 el_val_t __engram_load(el_val_t path)                       { return engram_load(path); }
 
 el_val_t __engram_get_node_json(el_val_t id)               { return engram_get_node_json(id); }
+el_val_t __engram_get_node_by_label(el_val_t label)        { return engram_get_node_by_label(label); }
 
 el_val_t __engram_search_json(el_val_t query, el_val_t limit) {
     return engram_search_json(query, limit);