Split kernel/OS packages out to home-os

[glennmichael123]

Context

The language repo currently contains substantial OS-level code that doesn't belong here:

Package	LOC
packages/kernel	43,741
packages/bootloader	2,087
packages/iommu	1,814
packages/syslog	1,553
packages/coredump	1,396
packages/dtb	1,384
packages/usb	1,356
packages/modsign	1,240
packages/tpm	1,198
packages/syscall	634
Total	~56k LOC

That's roughly 40% of the repo by package count and a huge chunk by LOC. Consequences:

• Clone time and disk usage are inflated for everyone working on the language
• Scope is muddled — contributors can't tell whether they should be reading kernel code to understand the compiler
• Two audiences (language users, OS users) collide in one issue tracker / docs site / CI

Proposal

• Move kernel/bootloader/iommu/syslog/coredump/dtb/usb/modsign/tpm/syscall to home-lang/home-os
• home-os depends on home-lang/home as a language toolchain (the way the linux kernel depends on gcc/clang)
• Keep small, language-relevant low-level packages in this repo (e.g. memory, volatile, intrinsics)
• Update docs: language repo docs cover the language only; OS docs live in home-os

Risks / open questions

• Do any compiler packages currently @import the OS packages? If so we need to invert the dependency cleanly
• CI for OS code is heavier (qemu, kernel boot tests) — splitting it out should actually speed up language CI

[glennmichael123]

Cross-ref: paired with home-lang/home-os#9 (the receiving side of the kernel/iommu/tpm/usb package move). The two issues should land in the same window to avoid prolonged broken imports across both repos.