refactor(background-agent): normalize task ID field naming

Rename BackgroundTask and attempt ID fields to camelCase across background-agent consumers while moving BackgroundManager construction to a single config object.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/tools/background-task/task-status-format.ts

@@ -62,7 +62,7 @@ ${truncated}
 | Agent | ${task.agent} |
 | Status | **${task.status}** |
 | ${durationLabel} | ${duration} |
-| Session ID | \`${task.sessionID}\` |${progressSection}
+| Session ID | \`${task.sessionId}\` |${progressSection}
 ${statusNote}
 ## Original Prompt