Fix jwt error in admin UI (#8140)

* add jwt token in weed admin headers requests

* add jwt token to header for download

* :s/upload/download

* filer_signing.read despite of filer_signing key

* finalize filer_browser_handlers.go

* admin: add JWT authorization to file browser handlers

* security: fix typos in JWT read validation descriptions

* Move security.toml to example and secure keys

* security: address PR feedback on JWT enforcement and example keys

* security: refactor JWT logic and improve example keys readability

* Update docker/Dockerfile.local

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Chris Lu <chris.lu@gmail.com>
Co-authored-by: Chris Lu <chrislusf@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

.gitignore

@@ -141,3 +141,4 @@ test/s3/iam/.test_env
 /test/erasure_coding/admin_dockertest/tmp
 /test/erasure_coding/admin_dockertest/task_logs
 weed_bin
+.aider*