feat: releases from GitHub first, then git.kebcloud.no; releases sets others

Updates and install.sh try the GitHub mirror, then git.kebcloud.no,
each with a short timeout, and download from the first server with the
release, checked against its checksums.txt. The releases config option
(and LAZYSECRETS_RELEASES for install.sh) lists other servers. The
release workflow copies each release to GitHub when GH_RELEASE_TOKEN is
set. The status pane's issues link points to GitHub.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/config/config.go

@@ -14,6 +14,7 @@ import (
 	"go.yaml.in/yaml/v3"
 
 	"git.kebcloud.no/keb/lazysecrets/internal/commands"
+	"git.kebcloud.no/keb/lazysecrets/internal/update"
 )
 
 type Config struct {
@@ -40,6 +41,10 @@ type Config struct {
 	// background; defaults to true. U and lazysecrets update work either
 	// way.
 	UpdateCheck *bool `yaml:"updateCheck"`
+	// Releases are the repositories updates come from, tried in order:
+	// on GitHub, or a Gitea or Forgejo server. Defaults to GitHub, then
+	// git.kebcloud.no (update.DefaultServers).
+	Releases []string `yaml:"releases"`
 	// Cache keeps what was loaded (never values) between runs, so lists
 	// show at once and refresh in the background; defaults to true.
 	Cache *bool `yaml:"cache"`
@@ -211,6 +216,11 @@ func (c Config) validate(path string) error {
 	if d := c.LoadDelay; d != nil && (*d < 0 || *d > 5*time.Second) {
 		return fmt.Errorf("%s: loadDelay: %s is not between 0s and 5s", path, *d)
 	}
+	for i, r := range c.Releases {
+		if _, err := update.API(r); err != nil || !strings.HasPrefix(r, "https://") {
+			return fmt.Errorf("%s: releases[%d]: %q is not an https:// repository address, like %s", path, i, r, update.GitHubRepo)
+		}
+	}
 	for i, v := range c.Providers.Azure.Vaults {
 		if !strings.HasPrefix(v, "https://") {
 			return fmt.Errorf("%s: providers.azure.vaults[%d]: %q is not an https:// vault URL", path, i, v)