Add per-tool-type cost breakdown (`top-tools` command)

[roeimichael]

Problem

CAT tracks cost per individual tool call and computes baselines per tool type, but never shows an aggregated view like "Bash consumed 45% of all tokens, Read consumed 30%". Users can't identify which tool types are the most expensive overall.

What to do

1. Add a SQL query for tool-type aggregation:

   SELECT task_type, COUNT(*) as call_count, 
          SUM(estimated_tokens) as total_tokens, 
          AVG(estimated_tokens) as avg_tokens 
   FROM tasks 
   WHERE estimated_tokens IS NOT NULL 
   GROUP BY task_type 
   ORDER BY total_tokens DESC

2. Add an API endpoint /api/tool-summary in src/context_analyzer_tool/collector/routes.py
3. Add a CLI command top-tools in src/context_analyzer_tool/cli.py that renders a ranked Rich table
4. (Optional) Add a panel in the TUI dashboard

Why this is a good first issue

It's a clean vertical slice: one SQL query → one API endpoint → one CLI command. Follow the pattern of existing commands like anomalies or context-cost.