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/boot/boot.splash.pas

@@ -13,6 +13,7 @@ unit boot.splash;
 interface
 
 uses
+    boot.mgr,
     driver.video.lvgl, driver.video, core.fmt.targa, core.gfx.texture, memory.heap;
 
 { Create the boot.splash screen and render the initial frame (0 %). }
@@ -82,6 +83,9 @@ var
     logoTexture: PTexture;
     logoDsc:     PLVImageDsc;
 
+var
+    Initialized : boolean = false;
+
 { ---- private helpers -------------------------------------------------- }
 
 { Build an lv_image_dsc_t that points to the decoded ARGB8888 pixel data. }
@@ -217,10 +221,13 @@ begin
 
     { Push the first frame to the display. }
     redraw;
+
+    Initialized := true;
 end;
 
 procedure update(percent: uint32; status: pchar);
 begin
+    if not Initialized then exit;
     if splashScreen = nil then exit;
 
     { Clamp to 0..100 }
@@ -232,11 +239,12 @@ begin
     redraw;
 
     { DEBUG: pause so each step is visible on screen }
-    busywait_500ms;
+    //busywait_500ms;
 end;
 
 procedure teardown;
 begin
+    if not Initialized then exit;
     if splashScreen = nil then exit;
 
     { Switch back to the screen that was active before the splash. }
@@ -260,6 +268,11 @@ begin
         kfree(void(logoTexture));
         logoTexture := nil;
     end;
+    Initialized := false;
 end;
 
+Initialization
+    boot.mgr.registerBoot('boot.splash', @init, 'Boot Splash Screen', 'core.panic');
+    boot.mgr.registerBoot('boot.splash.teardown', @teardown, 'Stop Splash Screen', BOOT_MGR_BARRIER_FINAL);
+
 end.