Phase 4: add structure, folding, and references

CHANGELOG.md

@@ -15,9 +15,17 @@
   structs, enums, unions, control flow including the `if x == { case }` switch
   form, and compiler directives. The full 714-file Jai distribution parses with
   no syntax errors; `JaiCorpusParserTest` is ratcheted at 100%.
+- Structure view with source-ordered declarations and nested procedure/aggregate
+  members.
+- Folding for blocks, nested comments, and multi-line here-strings.
+- Go-to-definition references for `#import` and `#load`, including project-relative
+  files and the local Jai module layout (`Name.jai` or `Name/module.jai`).
 
 ### Known gaps
 
 - `#asm` bodies are parsed as opaque blocks, so their assembly instructions do
   not have inner PSI.
-- Structure view, folding, and go-to-definition are not implemented yet.
+- `#asm` bodies remain intentionally opaque; assembly instructions do not have
+  inner PSI or structure entries.
+- Import resolution uses the project/module roots and the local Jai installation;
+  custom compiler `-import_dir` arguments are not discovered yet.