feature: boot.mgr replace hardcoded init sequence with dependency-driven boot manager

Introduce boot.mgr - a self-registering, dependency-ordered boot
initialization framework with barrier-based phasing and glob pattern
matching. Units now declare their own init procedures and dependencies
via registerBoot()/registerBarrier() in their initialization sections,
boot.mgr.run() topologically sorts and executes them.

- Add src/boot/boot.mgr.pas with topoSort, glob matching, barrier
  two-pass algorithm, and boot tree printer
- Gut src/asuro.pas (kmain): now just stores multiboot info, calls
  System.init(), boot.mgr.run, and yield()
- Add initialization sections with registerBoot() to 53 existing units
- Add new units: core.pas, test.pas, driver.storage.boot.pas,
  app.wasm.pas, app.bsod.pas (factored out of asuro.pas)
- Define 9 barrier phases: immediate -> early -> middle -> storage ->
  bus -> device -> bus.late -> late -> final
- Fix xHCI ISR: exclude PRC/WRC from PORTSC change bit clearing to
  prevent race with port reset busy-wait
- Fix driver.bus.usb.core fire_completion_hooks: guard against uint32
  underflow when CompletionHookCount = 0
- Move auto_mount_volumes from device barrier to late barrier so it
  runs after PCI scan discovers storage controllers
- Add toolchain/compile_initcalls.sh for boot entry extraction
- Add Boot Registration sections to all 51 doc files; create 4 new
  doc files; rewrite boot.mgr.md; update mkdocs.yml nav

doc/src/app/wasm/app.wasm.md

@@ -0,0 +1,28 @@
+# app.wasm
+
+WebAssembly VM backend initialiser.
+
+## Overview
+
+This unit initialises the Wasuro WebAssembly virtual machine backend. It wires up the VM's character output to the syslog interface and calls the main `wasm_init` entry point.
+
+## Boot Registration
+
+Registered with `boot.mgr` as `app.wasm` at the `final` barrier.
+
+## Dependencies
+
+- `boot.mgr`
+- `io.syslog`
+- `wasm.vm.io`
+- `wasm`
+
+## Procedures
+
+### init
+
+```pascal
+procedure init;
+```
+
+Sets the WASM VM's write-character callback to `io.syslog.logchar` and calls `wasm.wasm_init` to initialise the VM runtime.