* MM-68149: upgrade to Go 1.26.2
Update go directive in go.mod and .go-version.
* MM-68149: replace pointer helpers with Go 1.26 new()
Go 1.26 extends the built-in new() to accept an initial value expression,
making typed-pointer helpers like model.NewPointer(x), bToP(x), and boolPtr(x)
redundant. Replace every call site with new(x) and remove the now-unused
helper functions and their //go:fix inline directives.
* MM-68149: apply go fix for reflect API and format-string changes
- reflect.Ptr → reflect.Pointer (renamed in Go 1.18, deprecated alias removed in 1.26)
- reflect range-over-struct: for i := 0; i < t.NumField(); i++ → for field := range t.Fields()
and the equivalent for Methods() and interface types
- Fix format-string concatenation and variadic-arg mismatches flagged by go vet
* MM-68149: update JPEG fixtures and test infrastructure for Go 1.26 encoder
Go 1.26 ships a new image/jpeg encoder that produces slightly different output.
Regenerate all JPEG fixture files and switch the comparison helpers from
byte-equality to pixel-level comparison with a small per-channel tolerance,
so minor encoder drift across patch versions is handled automatically.
Add -update-fixtures flag to make it easy to regenerate fixtures after future
major Go upgrades. Document the update procedure in tests/README.md.
* MM-68149: CI check that go fix ./... produces no changes
* Fix real bugs flagged by CodeRabbit review
- group.go: set newGroup.MemberCount not group.MemberCount (member count
was populated on the wrong variable and lost before publish/return)
- file_test.go: guard compareImage(GetFilePreview) on the preview slice
length, not the thumbnail slice length (copy-paste error)
- config_test.go: remove duplicate MinimumLength assignment
* fixup! Fix real bugs flagged by CodeRabbit review
There was no check for embedded images which made "copy text" paste
the siteURL instead of the actual image content.
This does not change the behavior of actually rendering the image
which is how other sites behave as well.
https://mattermost.atlassian.net/browse/MM-49627
```release-note
NONE
```
