[PHP] fix: improve PHP procfs and utility coverage

[brandonpayton]

Why

Linux-compatible process metadata must be observable where Unix userland looks for it. PHP exposed two platform gaps: /proc/<pid>/stat did not place scheduler priority and nice in their Linux fields, and procfs metadata paths could outlive the process-table state they claimed to represent. The bundled ps also lacked the selection/output surface needed to consume that state.

What

• Emit /proc/<pid>/stat field 18 as scheduler priority (20 + nice) and field 19 as nice.
• Validate PID-scoped procfs entries for metadata, access, directory-change, and readlink operations, while preserving global /proc/net and making PID 0 an ordinary PID rather than a sentinel.
• Derive procfs PID visibility from authoritative process-table state: live processes and unreaped zombies remain visible; reaped Limbo entries do not.
• Extend posix-utils-lite ps with strict -p <pid[,pid]> and -o <fields> handling for pid, nice, and comm; missing or malformed selected processes are no longer fabricated as successful rows.
• Advance the posix-utils-lite build revision to 3 and make its build use the worktree-local SDK activation contract.
• Document the procfs scheduling/liveness surface and add kernel coverage for PID 0, missing PIDs, per-PID/global networking paths, and zombie-to-reaped visibility.

Review fixes

The original commit b4133e351 established the proc-stat layout and ps option support. Review found compile failures from nonexistent WasmStat::default(), an unwired liveness helper, PID-0/global-net aliasing, reaped entries remaining visible, permissive ps failure behavior, and a missing package revision/build-contract update. Append-only commit dbcb63c77 fixes those issues without rewriting the original contribution.

Verification

Replayed cleanly on the current #866 tip (91d13955f) and verified through the repository dev shell:

• kernel library: 970 passed, 0 failed
• musl rebuild: passed
• resolver-managed posix-utils-lite revision 3 source build: passed after the stale revision-2 archive was rejected by cache-key mismatch
• kernel Wasm build: passed
• Node runtime: ps -p 100 -o pid,nice reported the real process and exited 0; -p 999 emitted no fabricated row and exited 1
• cross-process runtime check on the repaired branch reported a target process at nice 5
• ABI snapshot/header/TypeScript consistency check: passed

The aggregate batch still receives the full ready-to-merge gate once, after all accepted constituents are present.

Provenance

Supersedes fork-headed PR #724. The original contribution remains commit b4133e351; the review repair is the appended commit dbcb63c77.

[github-actions]

Phase B-1 matrix build status — pr-744-staging

ABI v15. 67 built, 0 failed, 67 total.

Package	Arch	Status	Sha
libcurl	wasm32	built	35266304
libcxx	wasm32	built	a5091dda
libcxx	wasm64	built	e8edbf4b
libpng	wasm32	built	e38cc366
libxml2	wasm32	built	e13e27ba
libxml2	wasm64	built	9264562d
openssl	wasm32	built	ff868af9
openssl	wasm64	built	3c5d0c7f
sqlite	wasm32	built	6fb919c4
sqlite	wasm64	built	e027cc42
zlib	wasm32	built	1e6216c9
zlib	wasm64	built	ebc7e4a1
bc	wasm32	built	3a78fb67
bzip2	wasm32	built	2ddc287d
coreutils	wasm32	built	2a18f004
curl	wasm32	built	a1ab622d
dash	wasm32	built	a4ab83b1
diffutils	wasm32	built	89790993
dinit	wasm32	built	b793ac0f
fbdoom	wasm32	built	d9296a33
file	wasm32	built	6a1455c3
findutils	wasm32	built	1237e4d0
gawk	wasm32	built	57c5d5cf
git	wasm32	built	7c88a387
grep	wasm32	built	235ddcd5
gzip	wasm32	built	481eb543
kandelo-sdk	wasm32	built	18869e79
kernel	wasm32	built	7f3002ad
less	wasm32	built	a4f09d75
lsof	wasm32	built	cbd163cd
m4	wasm32	built	f0aff0d3
make	wasm32	built	250d1d25
mariadb	wasm32	built	bccf7260
mariadb	wasm64	built	3df390c0
modeset	wasm32	built	703cfd80
msmtpd	wasm32	built	ec5df629
nano	wasm32	built	1cea23a0
ncurses	wasm32	built	8c54f1c2
netcat	wasm32	built	361622f8
nginx	wasm32	built	d3f35370
php	wasm32	built	c81ee5be
posix-utils-lite	wasm32	built	66f52933
sed	wasm32	built	03befd20
spidermonkey	wasm32	built	99f07b7c
tar	wasm32	built	bede734f
tcl	wasm32	built	9070fddb
unzip	wasm32	built	6591e7ef
userspace	wasm32	built	c3d7e154
vim	wasm32	built	0d02b67d
wget	wasm32	built	04bb22d8
xz	wasm32	built	f54f1e93
zip	wasm32	built	19152752
zstd	wasm32	built	45fa0e20
bash	wasm32	built	74f8e39c
mariadb-test	wasm32	built	76d2883a
mariadb-vfs	wasm32	built	37cbbded
mariadb-vfs	wasm64	built	a37c83f6
nethack	wasm32	built	51827b74
node	wasm32	built	98ceb30e
spidermonkey-node	wasm32	built	8feaed4d
vim-browser-bundle	wasm32	built	63be56eb
nethack-browser-bundle	wasm32	built	6f83697f
rootfs	wasm32	built	54b2fa02
shell	wasm32	built	23a687f4
lamp	wasm32	built	4d78fa39
node-vfs	wasm32	built	a4993b66
wordpress	wasm32	built	98403f20

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