Make Docker and Apple container actually work with flycheck-phpstan

[zonuexe]

Makes Docker and Apple container actually work with flycheck-phpstan. Both were broken before #62 as well — #62 wired the runtimes up correctly, but three separate defects downstream meant a containerized check still reported nothing.

Stacked on #62. Please merge that first; this branch targets it.

The three defects

1. The analyzed file was passed as a host path. phpstan-get-command-args translated the config file with phpstan-normalize-path but not the target, so PHPStan answered Path /Users/.../test-docker.php does not exist and reported no errors. flymake-phpstan dodged this for modified buffers by normalizing the temp file itself, but was affected for unmodified ones.

Normalization now happens in phpstan-get-command-args, the one place that already knows about the mount point, and the redundant call in flymake-phpstan--create-temp-file is dropped so there is a single source of truth.

The --tmp-file branch needed more than translation: :temp-file creates the copy in the system temporary directory, which is not mounted and therefore invisible to the container. It now uses the in-place copy when containerized. That branch is only reachable for containers with phpstan-activate-editor-mode set to enabled, since version detection currently disables editor mode for them, but it was wrong either way.

2. The JSON report was ignored when prefixed. phpstan--parse-json deliberately skips everything before the first line starting with {, because the checker process merges STDERR into STDOUT. Its caller disagreed and only took the JSON branch when the whole output started with {. Docker stays quiet once the image is local, so this went unnoticed — but Apple container reports progress on STDERR for every run:

[0/6] [0s]
[1/6] Fetching image [0s]
...

so the JSON was never parsed and every check came back clean.

3. Failures were discarded. When there was no JSON at all, the fallback built a warning holding the raw output and then threw it away — data is a list of flycheck-error, so (plist-get data :files) returned nil. Every failure that stopped PHPStan from producing a report (broken config, bad -c path, a crash) was shown as a buffer with no errors. This is why the two defects above were silent rather than loud.

Verification

Ran Flycheck for real against ghcr.io/phpstan/phpstan on both runtimes:

case	before	after
docker, unmodified buffer	0 errors	2 errors ✅
container, unmodified buffer	0 errors	2 errors ✅
container, modified buffer (in-place copy)	0 errors	3 errors ✅
container, modified, phpstan-activate-editor-mode = enabled (--tmp-file)	0 errors	3 errors ✅
("docker" "run" ...) explicit form	0 errors	2 errors ✅

All match what local vendor/bin/phpstan reports for the same fixture, with no leftover temporary files. Local (non-container) execution is unchanged. With a config file PHPStan cannot use, the checker now reports Bootstrap file /.../tests/bootstrap.php does not exist. instead of nothing.

Still open

phpstan-editor-mode-available-p runs docker --version and parses d1c06ef out of Docker version 29.5.3, build d1c06ef as the PHPStan version, so editor mode stays silently disabled for container users — they get the in-place copy branch, which works. Fixing it needs a design decision (running IMAGE --version costs a container start per check, and the phpstan-executable-versions-alist cache is keyed by executable string), so it is left for a follow-up.