parse_statement parses every spec 7 form (assignment, call, if/else,
while, for/to/step, return, print, delete) and requires the line to end
after it. Expressions use precedence climbing over spec 8's levels: binary
operators left associative, unary not and - nesting rightwards, postfix
member access, calls, and indexing tightest. A syntax error is reported in
pass 1, unwinds to the statement, and skips the line; E03-S02's name,
member, and access checks now run from the parser in pass 2, replacing the
token scan. Expression nesting is bounded at 16 levels (E225).

Verified in x128: 31 fixtures, including the two statement fixtures that
were pending since E03-S01, a postfix trace golden for precedence and
associativity (both mutations caught), every statement form, and 15
independent syntax errors with recovery. Lowest stack pointer $A7. New
diagnostics E038-E042 and E225. The demo passes; its Vim typing is slowed
to 200 ms per key after one doubled keystroke.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>