D333 (#104): Input.AimStyle — N64 / PD damp / centred FPS-style aim on RMB

One F10 selector ("RMB aim style") instead of stacking toggles. CENTRED
routes RMB-held mouse motion to hipDirectCompute (FOV-scaled) and emits no
aim stick, so the game's aim integrator keeps the crosshair centred: the
behaviour the reporter found on Q (game L button), now on RMB. PD DAMP is
D332 (PR #96); legacy Input.PdMouseAim=1 migrates to it. Default N64 =
unchanged. Port-only.

Windows + Linux builds clean; bunker1 golden 3/3. Feel check owed.

docs/dev/findings-index.csv

@@ -210,3 +210,4 @@ D329,FIXED,The D318/D320 guard anim pin is a tick-granularity divergence:,"FIXED
 D330,FIXED,"#103 (v0.3.0, Win 11):","FIXED (port/src/input.c), build clean, bunker1 golden 3/3; mouse feel-check owed (a human must run it:"
 D331,FIXED,Ejected shell casings never rendered on PC:,"FIXED (gunfire.c #ifdef PORT, explicit template); PP7 casing verified on native Windows (before:"
 D332,FIXED,Reticule jitter in aim mode (RMB) —,FIXED (fix/mouse-pd-model) —
+D333,OPEN,"#104 (v0.3.0, Linux):","IMPLEMENTED (port/src/input.c + optionsoverlay.c, port-only); default N64 = unchanged; build + golden clean; feel check owed."