Recover agent-loop progress: lua/prolog/forth/erlang/haskell phases 1-2

Salvaged from worktree-agent-* branches killed during sx-tree MCP outage:
- lua: tokenizer + parser + phase-2 transpile (~157 tests)
- prolog: tokenizer + parser + unification (72 tests, plan update lost to WIP)
- forth: phase-1 reader/interpreter + phase-2 colon/VARIABLE (134 tests)
- erlang: tokenizer + parser (114 tests)
- haskell: tokenizer + parse tests (43 tests)

Cherry-picked file contents only, not branch history, to avoid pulling in
unrelated ocaml-vm merge commits that were in those branches' bases.

lib/lua/tests/parse.sx

@@ -0,0 +1,32 @@
+(define
+  lua-parse-tests
+  (list
+    (list "empty" "" (list (quote lua-block)))
+    (list
+      "int literal"
+      "return 42"
+      (list
+        (quote lua-block)
+        (list (quote lua-return) (list (list (quote lua-num) 42)))))
+    (list
+      "local"
+      "local x = 1"
+      (list
+        (quote lua-block)
+        (list
+          (quote lua-local)
+          (list "x")
+          (list (list (quote lua-num) 1)))))
+    (list
+      "binop"
+      "return 1 + 2"
+      (list
+        (quote lua-block)
+        (list
+          (quote lua-return)
+          (list
+            (list
+              (quote lua-binop)
+              "+"
+              (list (quote lua-num) 1)
+              (list (quote lua-num) 2))))))))