feat: detect and diagnose hvisor memory region overlap with root zone

[Inquisitor-201]

Summary

The root zone's ROOT_ZONE_MEMORY_REGIONS often overlaps with hvisor's own physical memory [skernel, __hv_end). This causes Linux to allocate and write to hvisor's page tables and heap, manifesting as seemingly random "unhandled MMIO fault" panics. This problem has appeared at least 10 times and is tracked in #310.

Changes

1. Compile-time overlap check (tools/check_hv_mem_overlap.py, integrated into make all)

• Reads skernel and __hv_end from the built ELF
• Parses ROOT_ZONE_MEMORY_REGIONS from board.rs (comment-aware)
• Fails the build with a clear diagnostic if any MEM_TYPE_RAM region overlaps hvisor's range
• Skips gracefully when symbols or board config aren't available

2. Runtime diagnostic (check_fault_in_hvisor_mem() in src/arch/aarch64/trap.rs)

• When handle_dabt encounters a stage-2 fault address within [skernel, __hv_end), prints:
  • The fault address and hvisor's range
  • The likely cause (guest DTB/config includes hvisor's memory)
  • Instructions to fix (exclude the range from memory_regions and DTB)
• Falls through to the original error handling if the address is outside hvisor's range

Testing

• Verified on rk3568: overlap check correctly blocks the build (hvisor at 0x60080000, RAM up to 0xf0000000)
• Verified on qemu-gicv3: passes cleanly when no overlap exists
• Intentionally misconfigured qemu-gicv3 RAM to overlap -> build correctly fails
• Self-test script validates symbol parsing and range boundary logic

Closes: #310
Related: #309