feat: proper IPC-based boot — init loads servers from storage via IPC, VirtIO GPU driver

Complete microkernel boot pipeline: adapter loads only init + storage + display
from disk. Init bootstraps all other servers by reading binaries from the
storage server via IPC, parsing ELF, creating processes, mapping pages, and
spawning threads.

New syscalls:
- CreateEndpoint: userspace endpoint creation with full capability grant
- DebugPutchar: debug output to UART from userspace
- MapPage: cross-process page mapping (init loads binaries into children)
- SpawnThreadIn: spawn thread in another process via capability

Key fixes:
- Per-process L1 page tables for VPN[2]=0 (prevents cross-process corruption)
- Separate kernel_pt from page_tables[0] (init pid=0 overwrote kernel PT ref)
- Thread Running state set in switch_to_next (syscalls rejected without it)
- Pending IPC results applied during context switch
- SIE disabled during boot (timer can't preempt into unready processes)
- User heap VA starts at 0x40000 (avoids shared buffer at 0x30000)
- RequestPages maps at user VAs via per-process heap allocator

VirtIO GPU:
- Adapter probes for GPU device, initializes resource/scanout/backing
- Display server writes to mapped framebuffer, flushes via GPU virtqueue
- 640x480 BGRA framebuffer with transfer-to-host and resource-flush

Storage server:
- Userspace VirtIO block driver using pre-mapped MMIO and DMA pages
- FAT16 filesystem reader serving file-read requests via IPC
- Shared buffer protocol: init writes filename, storage writes file data

Echo app for IPC testing (adapter-loaded echo proved the pipeline end-to-end).

Cargo.lock

@@ -6,6 +6,17 @@ version = 4
 name = "accessibility-server"
 version = "0.1.0"
 
+[[package]]
+name = "adapter-riscv"
+version = "0.1.0"
+dependencies = [
+ "domain",
+ "elf",
+ "kernel",
+ "platform",
+ "types",
+]
+
 [[package]]
 name = "alarm-server"
 version = "0.1.0"
@@ -41,6 +52,12 @@ version = "0.1.0"
 [[package]]
 name = "display-server"
 version = "0.1.0"
+dependencies = [
+ "server-framework",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
 
 [[package]]
 name = "domain"
@@ -49,6 +66,18 @@ dependencies = [
  "types",
 ]
 
+[[package]]
+name = "echo"
+version = "0.1.0"
+dependencies = [
+ "userspace",
+ "userspace-rt",
+]
+
+[[package]]
+name = "elf"
+version = "0.1.0"
+
 [[package]]
 name = "gatekeeper"
 version = "0.1.0"
@@ -57,18 +86,56 @@ version = "0.1.0"
 name = "gps-server"
 version = "0.1.0"
 
+[[package]]
+name = "hello"
+version = "0.1.0"
+dependencies = [
+ "userspace-rt",
+]
+
+[[package]]
+name = "init"
+version = "0.1.0"
+dependencies = [
+ "elf",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
+
 [[package]]
 name = "input-server"
 version = "0.1.0"
+dependencies = [
+ "server-framework",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
 
 [[package]]
 name = "kernel"
 version = "0.1.0"
+dependencies = [
+ "domain",
+ "platform",
+ "types",
+]
 
 [[package]]
 name = "keychain-server"
 version = "0.1.0"
 
+[[package]]
+name = "log-server"
+version = "0.1.0"
+dependencies = [
+ "server-framework",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
+
 [[package]]
 name = "media-index-server"
 version = "0.1.0"
@@ -88,6 +155,12 @@ version = "0.1.0"
 [[package]]
 name = "permission-manager"
 version = "0.1.0"
+dependencies = [
+ "server-framework",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
 
 [[package]]
 name = "platform"
@@ -108,14 +181,39 @@ version = "0.1.0"
 [[package]]
 name = "server-framework"
 version = "0.1.0"
+dependencies = [
+ "types",
+ "userspace",
+]
+
+[[package]]
+name = "session-server"
+version = "0.1.0"
+dependencies = [
+ "server-framework",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
 
 [[package]]
 name = "snake"
 version = "0.1.0"
+dependencies = [
+ "types",
+ "userspace",
+ "userspace-rt",
+]
 
 [[package]]
 name = "storage-server"
 version = "0.1.0"
+dependencies = [
+ "server-framework",
+ "types",
+ "userspace",
+ "userspace-rt",
+]
 
 [[package]]
 name = "sync-server"
@@ -140,3 +238,14 @@ version = "0.1.0"
 [[package]]
 name = "userspace"
 version = "0.1.0"
+dependencies = [
+ "types",
+]
+
+[[package]]
+name = "userspace-rt"
+version = "0.1.0"
+dependencies = [
+ "types",
+ "userspace",
+]