Fix TGUI29 metadata and demo fixture paths

[panDing19]

Problem

Two small metadata issues hurt reproducibility and result interpretation:

• TGUI29_loop_habit_expense_training/task.yaml declares task_id: TGUI30_loop_habit_expense_training, which pollutes batch summaries and makes task identity ambiguous.
• The ready-to-run demo uses repo-relative fixture paths, which break when the task is run from its task directory or inside a task-scoped container. Its Gmail query description also implies richer Gmail syntax than the mock supports.

Affected tasks

• TGUI29_loop_habit_expense_training
• examples/ready_to_run/T001_demo

Fix

• Correct TGUI29's task_id and fixture descriptions.
• Make demo fixture paths task-relative.
• Clarify that the demo Gmail query is a simple keyword filter over subject/from.

Tests

• uv run python - <<'PY' ... YAML parse check for TGUI29 and T001_demo task ids.