…as decimal (#954)

- Add support for 0o/0O prefix for explicit octal literals in lexer
- Change parser to explicitly handle bases instead of auto-detection
- Leading zeros without prefix are now treated as decimal (not octal)
- 0123 is now 123 (decimal), use 0o123 for octal 83
- 09 is now valid as decimal 9
- Add comprehensive tests for octal literals and base handling

Fixes #915

The objectTypeToEZ function was missing a case for *Map, causing
the internal type name "MAP" to leak in error messages instead of
showing the proper "map[keyType:valueType]" format.

Fixes #945

…or messages (#956)

Replace all direct .Type() calls in error messages with objectTypeToEZ()
or getEZTypeName() to prevent internal Go type names like INTEGER_OBJ,
MAP_OBJ from leaking into user-facing errors.

Changes:
- evaluator.go: ~30 instances replaced with objectTypeToEZ()
- interpreter/builtins.go: updated getEZTypeName() to include typed arrays/maps
- stdlib/builtins.go: 5 instances replaced with getEZTypeName()
- math.go: 1 instance replaced with getEZTypeName()
- json.go: 2 instances replaced with getEZTypeName()

Users now see friendly type names like "int", "[string]", "map[string:int]"
instead of "INTEGER_OBJ", "ARRAY_OBJ", "MAP_OBJ".

Fixes #948

json.decode() now requires a type argument at compile time. Previously,
calling json.decode(text) without a type would return an internal 'any'
type that users couldn't actually use in their code.

Changes:
- Add E13004 error code for missing type argument
- Update checkJsonModuleCall to require 2 arguments for decode
- Update getModuleMultiReturnTypes to return nil without type arg
- Update inferJSONCallType to return false without type arg
- Remove dead code for non-existent parse/parse_file functions

Closes #947

#958)

Both getEZTypeName and objectTypeToEZ now handle all object types:
- Range → "Range<int>"
- FileHandle → "File"
- Database → "Database"
- Reference → "Ref<innerType>"
- Char → "char" (added to objectTypeToEZ)
- Byte → "byte" (added to objectTypeToEZ)

Also exports FileHandle and Database type aliases from interpreter
package for consistency.

Closes #946