Fix misleading "Failed to auto-start" warnings on component creation

[Copilot]

Creating a reaction (or source) with autoStart: true logged a spurious WARN ... Failed to auto-start ... is already running, even though the component started fine. A genuine start failure was also logged at WARN rather than ERROR.

Root cause

DrasiLib::add_{reaction,source}_with_metadata already auto-starts the component when the server is running. The create/upsert handlers then called start_* again unconditionally — the second start hit an already-running component, producing the misleading warning (plus extra drasi-lib state-transition warnings for some component types).

Changes

• Guard the redundant start — handlers now only call start_* when the component is still Stopped (i.e. add did not auto-start it, e.g. server not yet running).
• Raise log level — genuine auto-start failures now log at ERROR instead of WARN.
• Applied consistently across reaction and source create + upsert handlers.

if auto_start {
    // add_*_with_metadata already auto-starts when the server is running;
    // only start here if it's still Stopped, and treat real failures as errors.
    if matches!(
        core.get_reaction_status(&reaction_id).await,
        Ok(ComponentStatus::Stopped)
    ) {
        if let Err(e) = core.start_reaction(&reaction_id).await {
            log::error!("Failed to auto-start reaction '{reaction_id}': {e}");
        }
    }
}

Tests

• Added test_create_reaction_auto_start_via_api: POSTs a reaction with autoStart: true and asserts it reaches Running. Logs confirm the component is now started exactly once.