[Kdecherf]

This change partially reverts #467 and #476 to rebuild a new image for wallabag 2.6.
This addresses the critical RCE vulnerabilities CVE-2026-109618 and CVE-2026-109619.

Main changes:

• PHP updated from 8.1.32 to 8.2.35
• Alpine updated from 3.19 to 3.22

We target PHP 8.2 as we already support it in the test matrix, without needing to release a new version.
Alpine version 3.22 is still supported for six months.

Quick grype scan:

$ grype wallabag/wallabag:2.6.14 | grep -E 'CVE-2026-109618|CVE-2026-109619'
 ✔ Loaded image                                                                                      wallabag/wallabag:2.6.14
 ✔ Parsed image                                       sha256:43746639f5f8abb4949394b69445f468e92c1c9430ef0986913d54e0f7994ff3
[...]

php81                      8.1.32-r0                                      apk           CVE-2026-109618      Critical  11.6% (96th)  10.7   
php81                      8.1.32-r0                                      apk           CVE-2026-109619      High      6.0% (93rd)   4.8    
336 packages from EOL distro "alpine 3.19.8" - vulnerability data may be incomplete or outdated; consider upgrading to a supported version

With this PR:

$ grype wallabag/wallabag:2.6.14.1 | grep -E 'CVE-2026-109618|CVE-2026-109619'
 ✔ Loaded image                                                                                    wallabag/wallabag:2.6.14.1
 ✔ Parsed image                                       sha256:5a4ae8c690656d3cc978a4da32d26559e0eb95dc7e71384b6a17cece0cffc3a4

Closes wallabag/wallabag#9094
Closes #480