feat(intelligence): add PainAggregator + SolutionGenerator (Chunk 2)

PainAggregator: cross-session pain point merge with confidence scoring,
rule-based frustration detection, and category classification.

SolutionGenerator: transforms high-confidence pain points into proposals
with concrete steps, skill hints, and lifecycle management.

5 Tauri commands registered: butler_list_pain_points, butler_record_pain_point,
butler_generate_solution, butler_list_proposals, butler_update_proposal_status.

desktop/src-tauri/src/lib.rs

@@ -355,6 +355,12 @@ pub fn run() {
             kernel_commands::mcp::mcp_stop_service,
             kernel_commands::mcp::mcp_list_services,
             kernel_commands::mcp::mcp_call_tool,
+            // Butler commands
+            intelligence::pain_aggregator::butler_list_pain_points,
+            intelligence::pain_aggregator::butler_record_pain_point,
+            intelligence::pain_aggregator::butler_generate_solution,
+            intelligence::pain_aggregator::butler_list_proposals,
+            intelligence::pain_aggregator::butler_update_proposal_status,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");