Let auto-build slots run their own build command under their own name

A branches.<name>.autoBuild.times entry is now either a plain HH:MM
string or an object with time, its own buildCommand, and a name, so a
nightly slot can run a fuller check than the on-commit builds. The
watcher passes the slot's command and name to the executor, persisted in
the build result — UI restarts, gittally retry, and the startup recovery
repeat a build with the command and name it originally ran under.

A named slot (e.g. master@nightly) gets its own pool: repository
grouping, retention count, branches-view row (sorted after its branch),
latest status, and permanent latest-green artifact link are keyed by the
build name, while origin lookups, gone-branch pruning, worktrees, and
Gitea links/statuses stay keyed by the real branch. Without a name,
slot builds share the branch's pool as before.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/main/kotlin/de/hoennig/gittally/commands/InitCommand.kt

@@ -199,7 +199,12 @@ class InitCommand(
                 requirePullRequest: false
                 autoBuild:
                   enabled: false        # whether to rebuild on schedule
-                  times: ["01:00"]      # UTC times HH:MM for scheduled builds
+                  # UTC times HH:MM for scheduled builds; an entry may carry its own
+                  # command and a name for a separate history/artifact pool:
+                  #   - time: "01:00"
+                  #     buildCommand: ./gradlew fullCheck
+                  #     name: main@nightly
+                  times: ["01:00"]
                 docker:
                   enabled: false        # run clean/build commands in a Docker container instead of natively
                   image: ""             # image for the build container; required when enabled