Phase 5: HAMT Persistent Vector + CI fixes

- Add lib/cljnim_pvec.nim: 32-way HAMT Persistent Vector with structural sharing
- Migrate ckVector from seq[CljVal] to PersistentVector[CljVal] in runtime
- Fix recursive pushLeaf bug (nil nodes at depth > 2)
- Fix defn/if return value bug: replace discard with result = in proc bodies
- Fix cljNth to accept CljVal index
- Add len and [] overloads for PersistentVector seq compatibility
- Add tests/test_pvec.nim (14 tests)
- Update .gitlab-ci.yml to nim:2.2.10 and add test_pvec
- Update docs/ROADMAP.md and add PHASE5_HAMT.md

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-image: nimlang/nim:2.0.0
+image: nimlang/nim:2.2.10
 
 stages:
   - test
@@ -10,10 +10,11 @@ test:
     - nim c -o:cljnim src/cljnim.nim
     - nim c -r tests/test_reader.nim
     - nim c -r tests/test_emitter.nim
+    - nim c -r tests/test_pvec.nim
     - ./cljnim compile examples/hello.clj /tmp/hello.nim
-    - nim c -r /tmp/hello.nim
+    - nim c --path:lib -r /tmp/hello.nim
     - ./cljnim compile examples/math.clj /tmp/math.nim
-    - nim c -r /tmp/math.nim
+    - nim c --path:lib -r /tmp/math.nim
   artifacts:
     paths:
       - cljnim
@@ -25,7 +26,6 @@ build-release:
     - main
   script:
     - nim c -d:release -o:cljnim src/cljnim.nim
-    - nim c -d:release -o:/tmp/bench_hello.nim
   artifacts:
     paths:
       - cljnim