kernel: make ProcessTable the sole task identity authority

[brandonpayton]

Why

Kandelo process and thread identities must come from authoritative kernel state. PR #966 removed one top-level spawn race, but the host still retained a JavaScript PID counter, selected process identifiers, and passed them into Rust. Thread-channel registration likewise accepted numeric thread identifiers from host callbacks. That split authority could create collisions or attach host transport state to the wrong task.

The Rust ProcessTable should be the only allocator and dispenser of process identifiers (PIDs) and thread identifiers (TIDs). Hosts should only consume identifiers returned by the kernel.

What changed

• Allocate every top-level process, fork child, posix_spawn child, and pthread TID from one monotonic ProcessTable sequence; PID 1 remains the synthetic init process.
• Introduce capability-based task identity construction and make process identity and thread-group membership immutable.
• Return allocated identifiers from kernel creation operations and remove host-side allocators, watermarks, and caller-selected identities.
• Validate exact task bindings and make clone channel attachment one-shot.
• Update lifecycle, signal, wait, and exec paths to preserve the single-authority invariant.
• Keep the Node.js and browser hosts on the same worker protocol.
• Bump the incompatible host/kernel contract from ABI 41 to ABI 42 and update generated ABI evidence, libc fork-child state refresh, package harnesses, tests, and documentation.

Validation

Run on this PR head:

• scripts/dev-shell.sh bash scripts/ci-run-test-suite.sh cargo-kernel — 1,202 tests passed.
• scripts/dev-shell.sh bash scripts/check-abi.sh — ABI snapshot, C header, TypeScript bindings, and ABI_VERSION are consistent.
• Focused host Vitest suites for spawn authority, clone authority, host parity, process/wait lifecycle, and Node teardown ordering — 74 tests passed.
• git diff --check — passed.

Run on the equivalent pre-restack code before the documentation-only conflict resolution:

• Full host Vitest — 1,548 tests passed; one package-artifact test timed out in the full run and passed alone in 3.2 seconds.
• Chromium browser CI — 49 passed, 5 intentionally skipped.
• Cross-browser suite — 57 passed.
• Rust documentation compile enforcement — 6 passed.
• musl rebuild — completed successfully.

The full libc, POSIX, and Sortix conformance suites and manual ./run.sh browser verification were not run.

ABI and artifacts

This is an incompatible ABI 42 transition. Existing kernel packages, programs, and VFS images must be rebuilt and published through the normal ABI release path. This change intentionally does not add a compatibility shim for ABI 41 artifacts.

[github-actions]

Phase B-1 matrix build status — pr-979-staging

ABI v42. 71 built, 0 failed, 71 total.

Package	Arch	Status	Sha
icu	wasm32	built	c3be8b38
libcurl	wasm32	built	3ca49a27
libcxx	wasm32	built	84f474c8
libcxx	wasm64	built	aa65876d
libiconv	wasm32	built	4679d9f9
libpng	wasm32	built	d9d70b09
libxml2	wasm32	built	f9ee5238
libzip	wasm32	built	474655ff
openssl	wasm32	built	2bc83c2a
openssl	wasm64	built	d0e14beb
sqlite	wasm32	built	62e57ce0
sqlite	wasm64	built	ec44ee5d
zlib	wasm32	built	a4795fce
zlib	wasm64	built	5b8b74f5
bc	wasm32	built	b3c85d98
bzip2	wasm32	built	9b236419
coreutils	wasm32	built	a2c25f4a
curl	wasm32	built	181dfa78
dash	wasm32	built	528d8154
diffutils	wasm32	built	3a9f570e
dinit	wasm32	built	b4804903
fbdoom	wasm32	built	fb4f11cf
file	wasm32	built	2350e713
findutils	wasm32	built	f902f30a
gawk	wasm32	built	f09ed1bf
git	wasm32	built	a0b8c426
grep	wasm32	built	fdc0e908
gzip	wasm32	built	2d7a4acd
hello	wasm32	built	484451f8
kandelo-sdk	wasm32	built	b689e510
kernel	wasm32	built	c540fd98
less	wasm32	built	494d36b0
lsof	wasm32	built	b470771f
m4	wasm32	built	0f442d94
make	wasm32	built	0734de42
mariadb	wasm32	built	929eed6a
mariadb	wasm64	built	0e20857d
modeset	wasm32	built	5845e800
msmtpd	wasm32	built	6fb3d8d7
nano	wasm32	built	e2503717
ncurses	wasm32	built	4d410941
netcat	wasm32	built	51ee2dd8
nginx	wasm32	built	40dd007a
php	wasm32	built	4db9b8be
posix-utils-lite	wasm32	built	bb45d861
ruby	wasm32	built	2e575709
sed	wasm32	built	375b5e4c
spidermonkey	wasm32	built	7e9dc2a0
tar	wasm32	built	6616c692
tcl	wasm32	built	318f8daa
unzip	wasm32	built	b7c2351b
userspace	wasm32	built	8485c073
vim	wasm32	built	40189e7e
wget	wasm32	built	26bc158c
xz	wasm32	built	e72c461d
zip	wasm32	built	6ded321c
zstd	wasm32	built	63d7ed99
bash	wasm32	built	e089fa28
mariadb-test	wasm32	built	e9147224
mariadb-vfs	wasm32	built	198719db
mariadb-vfs	wasm64	built	0ecc96f2
nethack	wasm32	built	e15aea37
node	wasm32	built	d7671179
spidermonkey-node	wasm32	built	d6a40d3d
vim-browser-bundle	wasm32	built	3757c205
nethack-browser-bundle	wasm32	built	7d5d286f
rootfs	wasm32	built	b38fe87d
shell	wasm32	built	e0fc80cc
lamp	wasm32	built	79bce7b8
node-vfs	wasm32	built	5cff1d67
wordpress	wasm32	built	95380b6f

_{Auto-generated; replaced on each push. Raw data in the publish-status workflow artifact.}