- Grammar: update pointer_type to support optional mut keyword;
LL(1) verified (56 named rules, no conflicts)
- AST: update Type enum with mutable: bool field for Pointer and
OpaquePointer variants
- Parser: consume optional mut token in parse_type; update all
existing pointer tests; add 4 new mut pointer tests (85 pass)
- VSCode extension: add *mut capture-group pattern for syntax
highlighting; update SYNTAX.md with pointer mutability table
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Compound assignment: +=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=
Shift: <<, >>
Each compound assignment token parses at the same precedence as `=`
(right-associative, lowest) and produces ExprKind::CompoundAssign.
Shifts parse between additive and multiplicative precedence.
GRAMMAR.ebnf and SYNTAX.md updated accordingly.
`=` was missing from the Pratt table, causing `a = b;` to fail with
"expected `;`, found `=`". Assignment is now BinaryOp::Assign with
binding power (2, 2) — lowest precedence, right-associative — so
`a = b = c` parses as `a = (b = c)`.
Add the LL(1) context-free grammar (GRAMMAR.ebnf), token and syntax
reference (SYNTAX.md), LL(1) verification tool (ll1_check.py), and a
fibonacci example demonstrating the language.
