Implement equality and inequality operators across three primitive types in the compiler and runtime. Add `bool_eqeq`/`bool_bangeq`, `num_eqeq`/`num_bangeq`, and `string_eqeq`/`string_bangeq` primitives that return false/true respectively when comparing against incompatible types. Update the parse rule table with `INFIX_OPERATOR` macros for `TOKEN_EQEQ` and `TOKEN_BANGEQ` at `PREC_COMPARISON` precedence. Include test files `bool_equality.wren`, `number_equality.wren`, and `string_equality.wren` covering cross-type comparisons and edge cases.
Remove the `sourceLength` field from the parser and `compile()` signature, switching to null-terminated strings read by `readFile()`. Replace the special `METHOD_CALL` method type with a `block_call` primitive that invokes `callBlock()` on the fiber, and move the `Fiber` and `CallFrame` structs into the public header so primitives can access them. Add a test for block calling via the new primitive.
