[PHP] fix: split host browser and SharedFS runtime fixes

[brandonpayton]

Supersedes fork-headed PR #738. This replacement keeps the same head commit (62a5771) but moves the PR head onto an Automattic/kandelo branch.

Why this is needed

Browser PHPT execution stresses host-backed mounts, SharedFS metadata, directory mutation behavior, DNS and output ordering, socket peeking, browser child output, exclusive creates, and VM interrupt timers. These are the host and runtime pieces needed for PHP tests to behave the same in browser and Node paths.

Why this shape makes sense

The group is large because the failures all live at the host, browser, and SharedFS boundary and are hard to validate independently without the same PHPT browser workload. Keeping them in one stacked layer makes the review surface explicit while preserving individual commits.

Why this is the correct fix

The changes tighten shared filesystem and browser-host semantics instead of weakening PHPT expectations. They make timestamps, directory reads, rename and unlink behavior, host-backed paths, child output, and interrupt delivery match the runtime contracts PHP relies on.

Stack

Base: integration/kd-6nz-php-phpt-fork-process-shm-base, after the fork/process/shared-memory replacement layer.

Verification

Branch-location correction only. Replacement head SHA matches fork-headed PR #738 exactly.

[github-actions]

Phase B-1 matrix build status — pr-757-staging

ABI v16. 66 built, 1 failed, 67 total.

Package	Arch	Status	Sha
libcurl	wasm32	built	05131d85
libcxx	wasm32	built	8da1dda5
libcxx	wasm64	built	3f9d7318
libiconv	wasm32	built	98ae39cc
libiconv	wasm64	built	364f191d
libpng	wasm32	built	57911579
libxml2	wasm32	built	c9190593
libxml2	wasm64	built	29606a80
openssl	wasm32	built	b830c422
openssl	wasm64	built	0ad8e76e
sqlite	wasm32	built	22892317
sqlite	wasm64	built	a488b172
zlib	wasm32	built	6258205e
zlib	wasm64	built	10905a61
bc	wasm32	built	f45b6fc6
bzip2	wasm32	built	ccaed6f7
coreutils	wasm32	built	9c2f9610
curl	wasm32	built	2a9910ba
dash	wasm32	built	dad4f1d0
diffutils	wasm32	built	243e8f6c
dinit	wasm32	built	8692ce28
fbdoom	wasm32	built	4de08e20
file	wasm32	built	37c5ed26
findutils	wasm32	built	abaccfbd
gawk	wasm32	built	5870aeeb
git	wasm32	built	3a505148
grep	wasm32	built	873a4b9d
gzip	wasm32	built	bbf648b6
kandelo-sdk	wasm32	built	6054195f
kernel	wasm32	failed	—
less	wasm32	built	cff77508
lsof	wasm32	built	b2808d0b
m4	wasm32	built	eeecbe81
make	wasm32	built	73a97016
mariadb	wasm32	built	d51494dd
mariadb	wasm64	built	019f4e3b
modeset	wasm32	built	26449a18
msmtpd	wasm32	built	8d5e57c3
nano	wasm32	built	e11bb2fe
ncurses	wasm32	built	077d7b78
netcat	wasm32	built	81674bbc
nginx	wasm32	built	a39e497d
php	wasm32	built	5a58aac5
posix-utils-lite	wasm32	built	b6e3e07f
sed	wasm32	built	2dbe649f
spidermonkey	wasm32	built	022c3dd5
tar	wasm32	built	79facabd
tcl	wasm32	built	950a960f
unzip	wasm32	built	87cc1e61
userspace	wasm32	built	3ca5b0d1
vim	wasm32	built	0d676ada
wget	wasm32	built	de9df728
xz	wasm32	built	52fe1260
zip	wasm32	built	a4a53388
zstd	wasm32	built	346b97c8
bash	wasm32	built	9d94677c
mariadb-test	wasm32	built	00b542dd
mariadb-vfs	wasm32	built	83005b2b
mariadb-vfs	wasm64	built	a79c1b0d
nethack	wasm32	built	799bbd26
node	wasm32	built	d57f5d71
spidermonkey-node	wasm32	built	fbcde318
vim-browser-bundle	wasm32	built	22e962ba
nethack-browser-bundle	wasm32	built	a1711c12
rootfs	wasm32	built	c314bfde
shell	wasm32	built	6ddcec14
node-vfs	wasm32	built	685a8cbd

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