Refactor handlers into SRP modules and add indicator/script tools

**Handler Refactoring:**
- Split monolithic handlers.rs (1468 lines) into 7 focused modules:
  - system.rs: verify_setup, healthcheck, list_symbols
  - experts.rs: list_experts, list_indicators, list_scripts, compile_ea
  - backtest.rs: run_backtest, get_backtest_status, cache_status, clean_cache
  - optimization.rs: run_optimization, get_optimization_results, list_jobs
  - analysis.rs: analyze_report, compare_baseline
  - setfiles.rs: read/write/patch/clone/diff set files
  - reports.rs: list/search/prune reports, archive, promote, annotate

**New Tools:**
- list_indicators: List custom indicators in MQL5/Indicators
- list_scripts: List scripts in MQL5/Scripts

**Config Updates:**
- Added indicators_dir and scripts_dir to Config model
- Auto-discovery for MQL5/Indicators and MQL5/Scripts paths
- Updated healthcheck to validate new directories

**Benefits:**
- Single Responsibility Principle: each module handles one domain
- Easier maintenance and testing
- Clear separation of concerns
- Reduced cognitive load when modifying handlers

src/tools/handlers/mod.rs

@@ -0,0 +1,109 @@
+use anyhow::Result;
+use chrono::Datelike;
+use serde_json::{json, Value};
+use std::path::Path;
+use crate::models::Config;
+
+mod system;
+mod experts;
+mod backtest;
+mod optimization;
+mod analysis;
+mod setfiles;
+mod reports;
+
+#[derive(Debug)]
+pub struct ToolHandler {
+    pub config: Config,
+}
+
+impl ToolHandler {
+    pub fn new(config: Config) -> Self {
+        Self { config }
+    }
+
+    pub async fn handle(&self, name: &str, args: &Value) -> Result<Value> {
+        match name {
+            // System handlers
+            "verify_setup" => system::handle_verify_setup(&self.config).await,
+            "list_symbols" => system::handle_list_symbols(&self.config).await,
+            "healthcheck" => system::handle_healthcheck(&self.config, args).await,
+            
+            // Expert/Indicator/Script handlers
+            "list_experts" => experts::handle_list_experts(&self.config, args).await,
+            "list_indicators" => experts::handle_list_indicators(&self.config, args).await,
+            "list_scripts" => experts::handle_list_scripts(&self.config, args).await,
+            "compile_ea" => experts::handle_compile_ea(&self.config, args).await,
+            
+            // Backtest handlers
+            "run_backtest" => backtest::handle_run_backtest(&self.config, args).await,
+            "get_backtest_status" => backtest::handle_get_backtest_status(&self.config, args).await,
+            "cache_status" => backtest::handle_cache_status(&self.config).await,
+            "clean_cache" => backtest::handle_clean_cache(&self.config, args).await,
+            
+            // Optimization handlers
+            "run_optimization" => optimization::handle_run_optimization(&self.config, args).await,
+            "get_optimization_status" => optimization::handle_get_optimization_status(&self.config, args).await,
+            "get_optimization_results" => optimization::handle_get_optimization_results(&self.config, args).await,
+            "list_jobs" => optimization::handle_list_jobs(&self.config).await,
+            
+            // Analysis handlers
+            "analyze_report" => analysis::handle_analyze_report(&self.config, args).await,
+            "compare_baseline" => analysis::handle_compare_baseline(&self.config, args).await,
+            
+            // Set file handlers
+            "read_set_file" => setfiles::handle_read_set_file(args).await,
+            "write_set_file" => setfiles::handle_write_set_file(args).await,
+            "patch_set_file" => setfiles::handle_patch_set_file(args).await,
+            "clone_set_file" => setfiles::handle_clone_set_file(args).await,
+            "diff_set_files" => setfiles::handle_diff_set_files(args).await,
+            "set_from_optimization" => setfiles::handle_set_from_optimization(args).await,
+            "describe_sweep" => setfiles::handle_describe_sweep(args).await,
+            "list_set_files" => setfiles::handle_list_set_files(&self.config).await,
+            
+            // Report handlers
+            "list_reports" => reports::handle_list_reports(args).await,
+            "search_reports" => reports::handle_search_reports(args).await,
+            "prune_reports" => reports::handle_prune_reports(&self.config, args).await,
+            "tail_log" => reports::handle_tail_log(&self.config, args).await,
+            "archive_report" => reports::handle_archive_report(&self.config, args).await,
+            "archive_all_reports" => reports::handle_archive_all_reports(&self.config, args).await,
+            "promote_to_baseline" => reports::handle_promote_to_baseline(&self.config, args).await,
+            "get_history" => reports::handle_get_history(args).await,
+            "annotate_history" => reports::handle_annotate_history(args).await,
+            
+            _ => Ok(json!({
+                "content": [{ "type": "text", "text": format!("Tool '{}' not implemented", name) }],
+                "isError": true
+            })),
+        }
+    }
+}
+
+// Helper functions used across modules
+pub(crate) fn dir_size(path: &Path) -> u64 {
+    if !path.exists() {
+        return 0;
+    }
+    walkdir::WalkDir::new(path)
+        .into_iter()
+        .filter_map(|e| e.ok())
+        .filter_map(|e| e.metadata().ok())
+        .filter(|m| m.is_file())
+        .map(|m| m.len())
+        .sum()
+}
+
+pub(crate) fn past_complete_month() -> (String, String) {
+    let now = chrono::Utc::now();
+    let today = chrono::NaiveDate::from_ymd_opt(now.year(), now.month(), 1)
+        .unwrap_or_else(|| chrono::NaiveDate::from_ymd_opt(2024, 1, 1).unwrap());
+    let last_of_prev = today.pred_opt()
+        .unwrap_or(today);
+    let first_of_prev = chrono::NaiveDate::from_ymd_opt(last_of_prev.year(), last_of_prev.month(), 1)
+        .unwrap_or(last_of_prev);
+    (
+        first_of_prev.format("%Y.%m.%d").to_string(),
+        last_of_prev.format("%Y.%m.%d").to_string(),
+    )
+}