refactor(type): migrate serializer from jit.ts to jit2.ts API

Migrate the entire serializer module to use the new unified expression tree
JIT architecture (jit2.ts). This provides:
- Single tree built once, consumed by both JIT and Exec modes
- Automatic CSP fallback when new Function() is blocked
- Cleaner API: Builder/Ref instead of Context/Slot

API changes:
- Context → Builder
- Slot<T> → Ref<T>
- jit.fn() → fn()
- ctx.when() → b.if_()
- ctx.callExpr() → b.call()
- ctx.newExpr() → b.new_()

All 1949 type package tests passing.

Author: marcj

packages/core/index.ts

@@ -18,6 +18,64 @@ export * from './src/network.js';
 export * from './src/perf.js';
 export * from './src/compiler.js';
 export * from './src/jit.js';
+// jit2 exports - Builder API for unified expression trees (JIT + Exec)
+// Note: Some exports overlap with jit.js (Arg, canJIT, etc.), so we selectively export
+export {
+    // Expression tree types
+    type LitExpr,
+    type InputExpr,
+    type VarExpr,
+    type GetExpr,
+    type AtExpr,
+    type CallExpr,
+    type NewExpr,
+    type ObjExpr,
+    type ArrExpr,
+    type EqExpr,
+    type NeqExpr,
+    type LtExpr,
+    type GtExpr,
+    type LteExpr,
+    type GteExpr,
+    type NotExpr,
+    type AndExpr,
+    type OrExpr,
+    type NullishExpr,
+    type TypeofExpr,
+    type IsTypeExpr,
+    type IsNullExpr,
+    type IsNullishExpr,
+    type HasExpr,
+    type LenExpr,
+    type TernaryExpr,
+    type InstanceofExpr,
+    type ConcatExpr,
+    type MapExpr,
+    type Expr,
+    // Statement types
+    type LetStmt,
+    type SetStmt,
+    type PushStmt,
+    type SetVarStmt,
+    type ExecStmt,
+    type ReturnStmt,
+    type ThrowStmt,
+    type IfStmt,
+    type LoopStmt,
+    type ForInStmt,
+    type SwitchStmt,
+    type Stmt,
+    type Block,
+    // Core classes
+    Ref,
+    VarRef,
+    Builder,
+    // Functions
+    arg,
+    fn,
+    fnJIT,
+    fnExec,
+} from './src/jit2.js';
 export * from './src/string.js';
 export * from './src/emitter.js';
 export * from './src/reactive.js';

packages/http/src/router.ts

@@ -97,13 +97,13 @@ export class UploadedFile {
 }
 
 // Register type guard for UploadedFile - validates that the file was provided by the framework
-serializer.typeGuards.registerClass(UploadedFile, (type, input, ctx, state) => {
+serializer.typeGuards.registerClass(UploadedFile, (type, input, b, state) => {
     // Check if input is an UploadedFile with valid validator symbol
-    return ctx.and(
-        ctx.isType(input, 'object'),
-        ctx.and(
-            ctx.not(ctx.isNull(input)),
-            ctx.callExpr((v: any, sym: symbol) => v.validator === sym, input, ctx.lit(UploadedFileSymbol)),
+    return b.and(
+        b.isType(input, 'object'),
+        b.and(
+            b.not(b.isNull(input)),
+            b.call((v: any, sym: symbol) => v.validator === sym, input, b.lit(UploadedFileSymbol)),
         ),
     );
 });