6114451e

By: Michael Lynch <git@mtlynch.io>

Simplify MediaItem.Filenames() with a per-type spec table

Replace two separate switches on MediaType (one for the full-size
extension, one for thumbnail/display filenames) with a single spec
table, removing duplicate thumbnail-building code shared by
MediaTypeImage and MediaTypeImageAnimated.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
configuredevShellx86_64-linuxbackendbackend-devcheck-bashcheck-frontendcheck-go-formattingcheck-go-test-packagescheck-trailing-newlinecheck-trailing-whitespacedeploy-to-flydiagramdocker-imagee2e-testsgo-testsimport-from-tinybeansjs-testslint-sqllittle-momentslittle-moments-devx86_64-linux