Add Window#attr_set and Window#attr_get

[shugo]

These wrap wattr_set() and wattr_get() respectively, exposing the full extended color pair number (> 255) that attrset/color_set cannot represent. attr_set(attrs, pair) sets both attributes and color pair; attr_get returns [attrs, pair] as a 2-element Array.

Both are guarded by HAVE_WATTR_SET / HAVE_WATTR_GET and fall back to rb_f_notimplement when unavailable.

[Copilot]

Pull request overview

This PR exposes the ncurses extended attribute API to Ruby by wrapping wattr_set() and wattr_get() as Window#attr_set and Window#attr_get. Unlike the existing attrset/color_set, these methods operate on a separate color pair integer (rather than embedding the pair inside a chtype), allowing pair numbers greater than 255. Both methods are guarded with HAVE_WATTR_SET/HAVE_WATTR_GET and fall back to rb_f_notimplement when unavailable.

Changes:

• Adds window_attr_set C function implementing Window#attr_set(attrs, pair) via wattr_set()
• Adds window_attr_get C function implementing Window#attr_get via wattr_get(), returning [attrs, pair]
• Registers both methods on cWindow via rb_define_method

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[Copilot]

The NUM2ULONG macro converts the Ruby Integer to unsigned long, but wattr_set's second parameter expects attr_t, which in ncurses is unsigned int (32-bit). On 64-bit platforms, unsigned long is 64-bit, so this causes an implicit narrowing conversion warning and potentially incorrect behavior if the value is wider than 32 bits. The correct conversion macro here should be NUM2UINT to match attr_t (which is an unsigned int-sized type). Compare to how the existing window_color_set at line 2811 simply passes attrs as-is after reading it via wattr_get.

Suggested change

	return (wattr_set(winp->window, NUM2ULONG(attrs), NUM2INT(pair), NULL) == OK) ? Qtrue : Qfalse;
	return (wattr_set(winp->window, NUM2UINT(attrs), NUM2INT(pair), NULL) == OK) ? Qtrue : Qfalse;

[Copilot]

ULONG2NUM(attrs) converts attrs (of type attr_t, which is unsigned int) to a Ruby Integer via unsigned long. This implicit widening from unsigned int to unsigned long is harmless on most platforms, but it is semantically imprecise. UINT2NUM(attrs) is the correct macro for an unsigned int-sized type. Additionally, INT2FIX(pair) is used for the pair value, but INT2FIX is only valid for values in the Fixnum range. Since NCURSES_PAIRS_T is an int supporting extended color pairs (which can be a large positive number), INT2NUM(pair) is the safer choice here. Notably, INT2FIX is used rather than INT2NUM throughout other parts of the codebase (e.g., line 1459), but the intent of attr_get is specifically to support large extended pair numbers, so losing that via an unsafe INT2FIX would be a bug if the pair number is large.

Suggested change

	return rb_ary_new3(2, ULONG2NUM(attrs), INT2FIX(pair));
	return rb_ary_new3(2, UINT2NUM(attrs), INT2NUM(pair));