refactor: update tool references from background_task to sisyphus_task

Update all references across:
- agent-usage-reminder: Update AGENT_TOOLS and REMINDER_MESSAGE
- claude-code-hooks: Update comment
- call-omo-agent: Update constants and tool restrictions
- init-deep template: Update example code
- tools/index.ts: Export sisyphus_task, remove background_task

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src/hooks/claude-code-hooks/index.ts

@@ -239,7 +239,7 @@ export function createClaudeCodeHooksHook(ctx: PluginInput, config: PluginConfig
       const cachedInput = getToolInput(input.sessionID, input.tool, input.callID) || {}
 
       // Use metadata if available and non-empty, otherwise wrap output.output in a structured object
-      // This ensures plugin tools (call_omo_agent, task) that return strings
+      // This ensures plugin tools (call_omo_agent, sisyphus_task, task) that return strings
       // get their results properly recorded in transcripts instead of empty {}
       const metadata = output.metadata as Record<string, unknown> | undefined
       const hasMetadata = metadata && typeof metadata === "object" && Object.keys(metadata).length > 0