fix: Handle repeated set-options-for-source calls before reboot

When set-options-for-source is called multiple times before rebooting,
the second call needs to find the target source's previous value in
the staged deployment's bootconfig (not the booted BLS, since we
haven't rebooted). Without this, the old kargs from the first call
would not be removed from the options line, causing duplication.

Fix by explicitly checking the target source in the staged bootconfig
after iterating known sources from the booted BLS entry.

Addresses review feedback from PR #2114.

Assisted-by: OpenCode (Claude claude-opus-4-6)

Author: jmarrero

crates/lib/src/loader_entries.rs

@@ -202,6 +202,18 @@ pub(crate) fn set_options_for_source_staged(
                 }
             }
         }
+        // Also check the target source directly in the staged bootconfig.
+        // This handles the case where set-options-for-source was called
+        // multiple times before rebooting: the target source exists in the
+        // staged bootconfig but not in the booted BLS entry.
+        let target_key = format!("{OPTIONS_SOURCE_KEY_PREFIX}{source}");
+        if !sources.contains_key(source) {
+            if let Some(val) = bootconfig.get(&target_key) {
+                if !val.is_empty() {
+                    sources.insert(source.to_string(), CmdlineOwned::from(val.to_string()));
+                }
+            }
+        }
         sources
     } else {
         // For booted deployments, parse the BLS file directly