refactor: apply newtypes throughout userspace API and display types

Every syscall stub now uses proper types from types/ — CapSlot,
EntryPoint, StackPointer, VirtualAddress, PageCount, ProcessId,
PermissionSet, Ticks. The compiler prevents swapping entry/stack,
passing a ProcessId where a CapSlot is expected, or using an
address as a page count.

New display types in types/display.rs:
  - Color(u32) with rgb() constructor
  - ScreenCoord(u16) for x/y positions
  - Dimension(u16) for width/height

Updated throughout:
  - userspace/syscall.rs: all params typed, returns Option instead
    of sentinel usize::MAX
  - server-framework: endpoint param is CapSlot
  - port-framebuffer: trait uses Color, ScreenCoord, Dimension
  - hw-virtio: DmaAddrs uses PhysicalAddress/VirtualAddress,
    GPU commands use Dimension
  - All servers, drivers, bins, apps updated for new signatures
  - permission-manager: process field uses ProcessId
  - PermissionSet: added bits() accessor

89 tests pass, full QEMU boot verified.

crates/drivers/framebuffer/virtio/src/lib.rs

@@ -4,6 +4,8 @@ use hw_virtio::mmio::MmioAccess;
 use hw_virtio::queue::{QueueAddrs, VirtioQueue};
 use hw_virtio::gpu::{self, GpuDmaAddrs};
 use port_framebuffer::Framebuffer;
+use types::address::{PhysicalAddress, VirtualAddress};
+use types::display::{Color, Dimension, ScreenCoord};
 
 const GPU_MMIO_VA: usize = 0x20000;
 const VQUEUE_VA: usize = 0x21000;
@@ -24,8 +26,8 @@ impl MmioAccess for GpuMmio {
 }
 
 struct PhysInfo {
-    cmd_pa: u64,
-    resp_pa: u64,
+    cmd_pa: PhysicalAddress,
+    resp_pa: PhysicalAddress,
     width: u16,
     height: u16,
 }
@@ -34,8 +36,8 @@ fn read_phys_info() -> PhysInfo {
     unsafe {
         let p = PHYSINFO_VA as *const u64;
         PhysInfo {
-            cmd_pa: core::ptr::read_volatile(p),
-            resp_pa: core::ptr::read_volatile(p.add(1)),
+            cmd_pa: PhysicalAddress::from_raw(core::ptr::read_volatile(p) as usize),
+            resp_pa: PhysicalAddress::from_raw(core::ptr::read_volatile(p.add(1)) as usize),
             width: core::ptr::read_volatile(p.add(3)) as u16,
             height: core::ptr::read_volatile(p.add(4)) as u16,
         }
@@ -46,50 +48,56 @@ pub struct VirtioFramebuffer {
     mmio: GpuMmio,
     queue: VirtioQueue,
     dma: GpuDmaAddrs,
-    width: u16,
-    height: u16,
+    width: Dimension,
+    height: Dimension,
     stride: usize,
 }
 
 impl VirtioFramebuffer {
     pub fn new() -> Self {
         let phys = read_phys_info();
+        let width = Dimension::new(phys.width);
+        let height = Dimension::new(phys.height);
         let stride = phys.width as usize * FB_BPP;
         Self {
             mmio: GpuMmio,
             queue: VirtioQueue::new(QueueAddrs::from_base(VQUEUE_VA)),
-            dma: GpuDmaAddrs { cmd_pa: phys.cmd_pa, cmd_va: CMDBUF_VA, resp_pa: phys.resp_pa },
-            width: phys.width,
-            height: phys.height,
+            dma: GpuDmaAddrs { cmd_pa: phys.cmd_pa, cmd_va: VirtualAddress::from_raw(CMDBUF_VA), resp_pa: phys.resp_pa },
+            width,
+            height,
             stride,
         }
     }
 }
 
 impl Framebuffer for VirtioFramebuffer {
-    fn width(&self) -> u16 { self.width }
-    fn height(&self) -> u16 { self.height }
+    fn width(&self) -> Dimension { self.width }
+    fn height(&self) -> Dimension { self.height }
 
-    fn write_pixel(&mut self, x: u16, y: u16, color: u32) {
-        if x >= self.width || y >= self.height { return; }
-        let offset = (y as usize) * self.stride + (x as usize) * FB_BPP;
-        unsafe { core::ptr::write_volatile((FB_VA + offset) as *mut u32, color); }
+    fn write_pixel(&mut self, x: ScreenCoord, y: ScreenCoord, color: Color) {
+        if x.raw() >= self.width.raw() || y.raw() >= self.height.raw() { return; }
+        let offset = (y.raw() as usize) * self.stride + (x.raw() as usize) * FB_BPP;
+        unsafe { core::ptr::write_volatile((FB_VA + offset) as *mut u32, color.raw()); }
     }
 
-    fn fill_rect(&mut self, x: u16, y: u16, w: u16, h: u16, color: u32) {
-        for dy in 0..h { for dx in 0..w { self.write_pixel(x + dx, y + dy, color); } }
+    fn fill_rect(&mut self, x: ScreenCoord, y: ScreenCoord, w: Dimension, h: Dimension, color: Color) {
+        for dy in 0..h.raw() {
+            for dx in 0..w.raw() {
+                self.write_pixel(ScreenCoord::new(x.raw() + dx), ScreenCoord::new(y.raw() + dy), color);
+            }
+        }
     }
 
-    fn clear(&mut self, color: u32) {
-        let total = self.width as usize * self.height as usize;
+    fn clear(&mut self, color: Color) {
+        let total = self.width.raw() as usize * self.height.raw() as usize;
         for i in 0..total {
-            unsafe { core::ptr::write_volatile((FB_VA as *mut u32).add(i), color); }
+            unsafe { core::ptr::write_volatile((FB_VA as *mut u32).add(i), color.raw()); }
         }
     }
 
     fn flush(&mut self) {
-        let w = self.width as u32;
-        let h = self.height as u32;
+        let w = self.width.raw() as u32;
+        let h = self.height.raw() as u32;
         gpu::transfer_to_host(&self.mmio, &self.queue, &self.dma, 1, 0, 0, w, h);
         gpu::resource_flush(&self.mmio, &self.queue, &self.dma, 1, 0, 0, w, h);
     }