⚡ [performance] Optimize task and step fetching to eliminate N+1 queries

[safal207]

💡 What:

• Refactored TaskManager.get_status to use a LEFT JOIN between tasks and steps tables, reducing the number of queries from 2 to 1 for a single task lookup.
• Added an optional include_steps parameter to TaskManager.list_tasks. When enabled, it fetches all steps for all tasks in a single additional query using a WHERE task_id IN (...) clause, rather than requiring N additional queries if steps were fetched per task.
• Implemented efficient dictionary-based grouping for batch results.

🎯 Why:
Fetching task steps inside a loop (or in multiple separate calls) created an N+1 query pattern, which leads to significant database overhead as the number of tasks grows. These optimizations ensure constant-time query complexity relative to the number of tasks for these common operations.

📊 Measured Improvement:

• Baseline (N+1): 0.0317 seconds for 50 tasks (2N+1 queries).
• Optimized (Batch): 0.0049 seconds for 50 tasks (2 queries total).
• Result: ~5x speedup for task list fetching with steps.

Correctness was verified by comparing the output of the N+1 pattern against the optimized batch pattern, ensuring identical data structures.

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PR created automatically by Jules for task 17682937582860378622 started by @safal207

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