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/core/core.md

@@ -0,0 +1,27 @@
+# core
+
+Core subsystem late initialiser.
+
+## Overview
+
+This unit performs late-stage core initialisation that depends on the RTC being available. Currently it seeds the pseudo-random number generator from the real-time clock.
+
+## Boot Registration
+
+Registered with `boot.mgr` as `core` at the `late` barrier.
+
+## Dependencies
+
+- `boot.mgr`
+- `core.rand`
+- `driver.timer.rtc`
+
+## Procedures
+
+### init
+
+```pascal
+procedure init;
+```
+
+Seeds `core.rand.srand` with a value derived from the current RTC date/time (seconds, minutes, hours, day), ensuring the PRNG produces different sequences across reboots.

doc/src/core/core.panic.md

@@ -29,6 +29,10 @@ If `init` has not been called before a panic (early boot panic), the unit gracef
 - `core.strings` — string comparison for gfxd process detection
 - `core.gfx.color` — TRGB32 colour type for direct pixel drawing
 
+## Boot Registration
+
+Registered with `boot.mgr` as `core.panic`, depending on glob `arch.*.panic` (waits for all matching entries).
+
 ## Constants
 
 ### MAX_REGISTER_ENTRIES