feat: implement context switching, SavedContext with pc/status fields, wire all syscall outcomes and timer preemption

crates/adapter-riscv/src/main.rs

@@ -64,7 +64,7 @@ extern "C" fn kmain() -> ! {
     hw::plic::Plic::init();
     uart.write_str("k-os: traps and timer initialized\n");
 
-    let riscv_platform = platform::RiscVPlatform::new();
+    let riscv_platform = platform::RiscVPlatform::new(kernel_pt as *const mmu::PageTable as usize);
     let pool = domain::memory::page_pool::PagePool::new(
         types::address::PhysicalAddress::from_raw(board::USER_POOL_BASE),
         board::USER_POOL_PAGES,