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

src/app/app.bsod.pas

@@ -0,0 +1,33 @@
+unit app.bsod;
+
+interface
+
+uses
+    io.stdio,
+    debug.tracer,
+    core.panic;
+
+procedure init;
+
+implementation
+
+procedure terminal_command_bsod(params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);
+begin
+    push_trace('kernel.terminal_command_bsod');
+
+    if paramCount(params) > 1 then begin
+      core.panic.panic(getparam(0, params), getparam(1, params), nil);
+    end else begin
+        io.stdio.bufWriteStrLn(stderr_buf, 'Invalid number of params.');
+        io.stdio.bufWriteStrLn(stderr_buf, 'Usage: bsod <error> <info>');
+    end;
+
+    pop_trace;
+end;
+
+procedure init;
+begin
+    io.stdio.registerCommand('BSOD', @terminal_command_bsod, 'Force a Panic Screen.');
+end;
+
+end.