Implement unary negation for numbers and logical not for booleans, introduce PREC_ASSIGNMENT and PREC_UNARY precedence levels, refactor parse functions to accept allowAssignment parameter, add assignment tests for global/local/chained/error cases, and update if-syntax to support statement branches and assignment in conditions.
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.
Implement parenthesized expression parsing in the primary() function by matching TOKEN_LEFT_PAREN, recursively calling expression(), and consuming TOKEN_RIGHT_PAREN. Add grammar test cases in test/grammar.wren verifying correct operator precedence with parentheses, including nested grouping expressions.
