errors: thread operand hints into arith & bitwise type errors

[davydog187]

Summary

Closes the remaining half of #252 — the wording already matched PUC-Lua;
only the trailing (global 'X') / (local 'X') / (upvalue 'X') /
(field 'X') hint suffix was missing.

• Codegen: every arithmetic / bitwise binop / unop now resolves its
  operands' lexical origin via the existing name_hint/2 and bakes the
  result into the instruction tuple. Same pattern as :get_field,
  :set_field, :call, :self.
• Executor: raise_arith_type_error/4, to_integer!/4, and
  float_to_integer!/3 now take a hint and append it via
  format_target_hint/1. The safe_* helpers pick the failing
  operand's hint correctly.
• Dispatcher (B5d v2): bytecode encoding preserves hints, and
  dispatcher_binop / dispatcher_unop thread them through to the
  same raise paths — so compiled prototypes also surface the hint.
• Suite skips: math.lua / sort.lua / errors.lua /
  strings.lua skip reasons updated to drop the now-resolved
  "checkerror format mismatch" blocker. Remaining blockers are
  behavioural (finite math.huge, timeouts, parse-error templates)
  and tracked separately.

Examples

Expression	Before	After
return foo + 1 (foo nil global)	arithmetic on a nil value	arithmetic on a nil value (global 'foo')
local x; return -x	arithmetic on a nil value	arithmetic on a nil value (local 'x')
local t={}; return t.x + 1	arithmetic on a nil value	arithmetic on a nil value (field 'x' on local 't')
return math.huge << 1	number has no integer representation	number has no integer representation (field 'huge' on global 'math')
local s='x'; return s << 1	bitwise operation on a string value	bitwise operation on a string value (local 's')

Test plan

• mix test — 1963 passed (was 1955), 25 skipped — 8 new pin tests
  for the hint suffix across all four origin tags × arithmetic /
  bitwise / integer-representation.
• mix format --check-formatted
• mix compile --warnings-as-errors
• mix dialyzer — no new errors (pre-existing one in
  tasks/suite_runner.ex unchanged).
• test/lua/vm/error_format_test.exs — arithmetic type error carries operand hint + bitwise type error carries operand hint
  describe blocks pin every rendering.

Closes #252.
Plan: A40