- Add blaise_exc.c to RTL: _PushExcFrame, _PopExcFrame, _Raise,
_CurrentException, _Reraise using thread-local setjmp/longjmp frames
- Update rtl/Makefile to compile and archive blaise_exc.c
- Rewrite EmitTryFinallyStmt: alloc16 frame on stack, push+setjmp at try
entry, finally body emitted on both normal and exception paths, _Reraise
propagates to enclosing handler on exception path
- Rewrite EmitTryExceptStmt: same frame setup, except handler entered via
jnz on setjmp return, _PopExcFrame before handler body
- Add 6 codegen tests for setjmp-based dispatch patterns (460 tests total)
- Update design doc: mark try/except/finally as Done, update next steps
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