…alls

- User-defined module functions with multiple return values now correctly
  propagate ret_types to the temp symbol, fixing multi-var destructuring
  like `mut a, b = mod.func()` which previously gave E3006 false positive
- E3040 check now catches single-var assignment of multi-return module
  calls, preventing C type errors from leaking through
- Added stdlib argument count validation table covering all stdlib modules,
  so missing/extra args to functions like io.read_file() are caught by the
  typechecker instead of leaking C compiler errors

All relative paths in io, csv, and sqlite functions resolve from the
process working directory, not from source file locations.

Added a table-driven first-argument type checker covering strings, io,
maps, crypto, encoding, regex, json, csv, bytes, and sqlite modules.
Passing the wrong type (e.g. int to strings.to_upper, string to
maps.has_key) now emits E3001 at compile time instead of leaking C
compiler errors. Also added a general first-arg-must-be-array check
for all arrays.* functions.

…ype checks

Add NODE_RANGE_EXPR to rewrite_labels() so file-scope constants
referenced inside range() expressions get properly rewritten during
multi-file import merging. Also extend E3085 validation to catch
type mismatches when using in/!in with range() (e.g. string !in
range(1, 50)).

Add arrays.remove(arr, value) which removes the first occurrence of
a value from an array. Supports int, float, and string element types.
Wired through all four layers: C implementation, header, typechecker,
and codegen.

…ternal name prefixes

Two fixes:

1. Multi-return type parser used read_type_name() for unnamed return
slots, which only handles simple identifiers. Array types like [string]
were tokenized as separate return types, and map[K:V] was misread as
a named return. Switch to parse_complex_type() and add map/func to
the is_type disambiguation.

2. Import merging prefixes declaration names (e.g. foo -> mod_foo) but
these internal names leaked into every error message. Add original_name
fields to all declaration AST structs, preserve them during merging,
and use display-name macros in all 28+ error/warning locations so
users always see the names they wrote.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>