Achieve 100% Core compliance, implement CATCH/THROW

Core word set: 0 errors on Gerry Jackson's forth2012-test-suite/core.fr
- Fix POSTPONE for non-immediate words via COMPILE, mechanism
- Fix double-DOES> (WEIRD: pattern) with does-body scanning and
  runtime patching via _DOES_PATCH_
- Implement CATCH/THROW exception handling using wasmtime trap
  mechanism with stack pointer save/restore
- 232 tests passing

CLAUDE.md

@@ -1,9 +1,11 @@
 # WAFER Project Conventions
 
 ## What is WAFER?
+
 WAFER (WebAssembly Forth Engine in Rust) is an optimizing Forth 2012 compiler targeting WebAssembly. Currently a working Forth system with 70+ words and JIT compilation.
 
 ## Architecture
+
 - Each Forth word compiles to its own WASM module via `wasm-encoder`
 - Modules share memory, globals (dsp/rsp), and a function table via wasmtime imports
 - IR-based compilation: Forth -> `Vec<IrOp>` -> WASM codegen -> wasmtime instantiation
@@ -11,6 +13,7 @@ WAFER (WebAssembly Forth Engine in Rust) is an optimizing Forth 2012 compiler ta
 - Primitives: either IR-based (compiled to WASM) or host functions (Rust closures in wasmtime)
 
 ## Key Files
+
 - `crates/core/src/outer.rs` -- ForthVM: the main runtime, outer interpreter, compiler, all primitives
 - `crates/core/src/codegen.rs` -- IR-to-WASM translation, module generation, wasmtime execution tests
 - `crates/core/src/dictionary.rs` -- Dictionary data structure with create/find/reveal
@@ -21,11 +24,13 @@ WAFER (WebAssembly Forth Engine in Rust) is an optimizing Forth 2012 compiler ta
 ## Adding a New Word
 
 **IR primitive** (simple stack/arithmetic/logic -- preferred when possible):
+
 ```rust
 self.register_primitive("WORD_NAME", false, vec![IrOp::Dup, IrOp::Mul])?;
 ```
 
 **Host function** (needs Rust logic -- I/O, dictionary manipulation, complex stack access):
+
 ```rust
 let func = Func::new(&mut self.store, func_type.clone(), move |mut caller, _params, _results| {
     // manipulate memory/globals directly
@@ -38,18 +43,21 @@ self.register_host_primitive("WORD_NAME", false, func)?;
 Handle in `interpret_token_immediate()` or `compile_token()` as a special case.
 
 ## Code Style
+
 - `cargo fmt --all` and `cargo clippy --workspace` must pass with no warnings
 - Every public function needs a doc comment
 - Use `thiserror` for error types in core crate, `anyhow` for CLI
 - Prefer returning `Result` over panicking
 
 ## Testing
+
 - Run `cargo test --workspace` before committing (currently 185 tests)
 - Forth 2012 compliance: `cargo test -p wafer-core --test compliance`
 - Test helper in outer.rs: `eval_output("forth code")` returns printed output as String
 - Test helper: `eval_stack("forth code")` returns data stack as Vec<i32>
 
 ## Key Principles
+
 1. Correctness first, performance second
 2. Maximize Forth, minimize Rust (self-hosting goal -- not yet started)
 3. Test-driven: if it's not tested, it doesn't work