Fix CORS handling

Don't forward the CORS preflight request to the auth middleware.

References: https://todo.xenrox.net/~xenrox/ntfy-alertmanager/25

Support templates

The body of the notification can now be rendered from a template.

readme: Add note about markdown formatting

Fix bugs in multialert message format

Support markdown in multi-alert mode as well

docker: Read version from justfile

docker: Build smaller binaries

Compile with ldflags "-w" and "-s".

"-w" removes DWARF debugging information
"-s" removes the symbol table

Support markdown format

Implements: https://todo.xenrox.net/~xenrox/ntfy-alertmanager/16

See: https://codeberg.org/xenrox/ntfy-alertmanager/issues/6

Build and publish arm64 Docker images

https://codeberg.org/xenrox/ntfy-alertmanager/issues/16

fix(charts): update version and adjust Probes to health

Upgrade dependencies

docker/helm: Release 0.5.0

docker: Add healthcheck

Log successful shutdown

Log IP, user-agent on basic auth failure

Can be used in combination with a tool like fail2ban.

Add a "health" endpoint

fix(helm): add option to override global image part and add docs

fix(authMiddleware): send 401 if no basicAuth is given

ci: Fix working directory for helm linting

justfile: Multiple changes for helm handling

Use "helm lint" instead of "ct lint" for now - "ct" lint is not packaged
correctly.

Only push the helm chart to Codeberg.