D335: native widescreen, HUD + front end (Option B Phase 3)

HUD elements now keep 4:3 proportions via fast3d's EXT aspect modes (the PD
pattern): watch, gauge bars, messages/title card, upper text and countdown
CENTER; ammo RIGHT (right hand) / LEFT (left hand). The front end is
pillarboxed (whole menu_jump_constructor_handler CENTER) and the menu
pointer is mapped into the pillarbox. port/include/hudaspect.h emits only
when native widescreen is on and the window is wider than 4:3, so 4:3 and
native-off stay byte-identical. Rule-2 approved.

Verified with 16:9/21:9 captures (HUD, watch, title card, legal, file
select, gun barrel); golden 3/3; Win + Linux builds. Gun-barrel circle
leaks into the bars while sliding in -> GRAPHICS-BACKLOG D335a.

port/src/input.c

@@ -1052,6 +1052,18 @@ unsigned inputComputePad(int idx, signed char *stick_x, signed char *stick_y)
                         }
                         if (mx != lastMenuMouseX || my != lastMenuMouseY) {
                             double fx = (double)mx / (double)ww;
+                            /* D335: under native widescreen the front end is
+                             * pillarboxed to a centred 4:3 region
+                             * (front.c menu_jump_constructor_handler), so map
+                             * the pointer across that region, not the window. */
+                            {
+                                extern f32 portNativeAspect(void);
+                                f32 na = portNativeAspect();
+                                if (na > (4.0f / 3.0f)) {
+                                    double vis = (4.0 / 3.0) / (double)na;   /* visible width fraction */
+                                    fx = (fx - (1.0 - vis) * 0.5) / vis;
+                                }
+                            }
                             double fy = (double)my / (double)wh;
                             if (fx < 0.0) fx = 0.0; else if (fx > 1.0) fx = 1.0;
                             if (fy < 0.0) fy = 0.0; else if (fy > 1.0) fy = 1.0;