fix: arena leak in compile() — token/sig strings now tracked

Wrapped compile() body in el_arena_push/pop so the arena is active
before lex() and scan_fn_sigs(). Previously both ran with
_tl_arena_active=0, leaking all token and signature strings permanently.
Also prevents inner pop(mark=0) calls from deactivating the arena
between per-function scopes. Verified: self-host PASS, RSS stable.

lang/el-compiler/src/compiler.el

@@ -23,12 +23,22 @@ import "codegen-js.el"
 // Uses JIT function-at-a-time streaming: parse one decl → emit C → discard AST.
 // Peak memory is O(one function's AST) instead of O(whole program AST).
 fn compile(source: String) -> String {
+    // Top-level arena scope: activates the string arena before lex() so that
+    // ALL strdup allocations (token strings, sig strings, codegen fragments)
+    // are tracked and freed on pop. Without this, lex() and scan_fn_sigs()
+    // run before any push, leaving _tl_arena_active=0 and leaking every
+    // token string. Also prevents inner pop(mark=0) calls from deactivating
+    // the arena between per-function scopes.
+    let top_mark: Any = el_arena_push()
     let tokens: [Any] = lex(source)
     // Fast pre-scan: collect fn signatures + program kind without building
     // full expression ASTs. O(tokens) time, minimal allocation.
     let sigs: [Map<String, Any>] = scan_fn_sigs(tokens)
     // Stream parse-emit: parse one decl at a time, emit C, discard.
+    // All output written to stdout via println before pop.
     codegen_streaming(tokens, sigs, source)
+    el_arena_pop(top_mark)
+    ""
 }
 
 // compile_js — full pipeline (JS target, module mode): source string -> JS source string