Report unknown size instead of passing false or 0 bytes to the inner validator

[ZamboniL]

Size casted the return of filesize() to an integer, and (int) false === 0, so a
filename that does not exist or is not readable validated as 0 bytes. Every upper-bound
check passed on a file that was never there:

v::size('KB', v::lessThan(2))->assert('/path/that/does/not/exist');
// Validation passes successfully

SplFileInfo::getSize() throws when stat fails, so the same missing file escaped as an
uncaught RuntimeException instead of a validation failure; its documented return type is
int|false, so overrides may return false rather than throw (Symfony's Stream
does exactly that). PSR-7 streams and uploaded files may legitimately report null for an
unknown size, and that was reported as TEMPLATE_WRONG_TYPE, which is misleading: the type
is fine, only the size is not knowable.

Check the input type up front, so unsupported types keep reporting TEMPLATE_WRONG_TYPE,
and report a supported input whose size cannot be determined under the new
TEMPLATE_UNKNOWN_SIZE. Guard filesize(), catch the RuntimeException from SplFileInfo
and narrow every getSize() result with is_int(). getSize() was also being called twice
per evaluation; it is now called once.

Inputs that previously validated against a bogus 0 now fail, which is a behaviour change. The existing
template constant and message are untouched.

---

There is no open issue for this. I found it in a Symfony API validating user-supplied
files, which arrive as HttpFoundation\File\File an SplFileInfo subclass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.14%. Comparing base (4bd2d68) to head (f78e012).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1843      +/-   ##
============================================
- Coverage     97.16%   97.14%   -0.03%     
- Complexity     1087     1096       +9     
============================================
  Files           198      198              
  Lines          2542     2554      +12     
============================================
+ Hits           2470     2481      +11     
- Misses           72       73       +1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[alganet]

Looks good to me! Thanks for your contribution 🐼

I'll wait a couple of days to give a chance for @henriquemoody to review it.

I would probably remove the // coments. It's our style to not have them, but currently nothing enforces their absence so I won't require you to remove them (would be nice though; that would also be best as an amend instead of a separate commit).

This will probably be in either 3.2 or 4.0 (the main branch will increase one of those counters soon). Let me know if you need a backport for a 3.1.x or 2.x release, if it's something important I can work it out.

[ZamboniL]

Thank you for the quick response, I deleted the comments with a ammend.

I can wait til the next minor/major, no problem!

[henriquemoody]

Thanks for those changes, @ZamboniL!

I made a few comments, all nick pick. Not required, but would make the code a bit neater.

@alganet, I'm fine if you want to merge it as is.

[ZamboniL]

Nits applied, thanks for the review.