Implement real-time process monitoring and fix UI hardcoded data

This commit addresses several key issues identified during development:

Major Changes:
- Replace hardcoded top CPU/RAM process display with real system data
- Add intelligent process monitoring to CpuCollector using ps command
- Fix disk metrics permission issues in systemd collector
- Optimize service collection to focus on status, memory, and disk only
- Update dashboard widgets to display live process information

Process Monitoring Implementation:
- Added collect_top_cpu_process() and collect_top_ram_process() methods
- Implemented ps-based monitoring with accurate CPU percentages
- Added filtering to prevent self-monitoring artifacts (ps commands)
- Enhanced error handling and validation for process data
- Dashboard now shows realistic values like "claude (PID 2974) 11.0%"

Service Collection Optimization:
- Removed CPU monitoring from systemd collector for efficiency
- Enhanced service directory permission error logging
- Simplified services widget to show essential metrics only
- Fixed service-to-directory mapping accuracy

UI and Dashboard Improvements:
- Reorganized dashboard layout with btop-inspired multi-panel design
- Updated system panel to include real top CPU/RAM process display
- Enhanced widget formatting and data presentation
- Removed placeholder/hardcoded data throughout the interface

Technical Details:
- Updated agent/src/collectors/cpu.rs with process monitoring
- Modified dashboard/src/ui/mod.rs for real-time process display
- Enhanced systemd collector error handling and disk metrics
- Updated CLAUDE.md documentation with implementation details

agent/src/collectors/error.rs

@@ -2,52 +2,21 @@ use thiserror::Error;
 
 #[derive(Debug, Error)]
 pub enum CollectorError {
-    #[error("Command execution failed: {command} - {message}")]
-    CommandFailed { command: String, message: String },
-
-    #[error("Permission denied: {message}")]
-    PermissionDenied { message: String },
-
-    #[error("Data parsing error: {message}")]
-    ParseError { message: String },
-
-    #[error("Timeout after {duration_ms}ms")]
-    Timeout { duration_ms: u64 },
-
-    #[error("IO error: {message}")]
-    IoError { message: String },
-
+    #[error("Failed to read system file {path}: {error}")]
+    SystemRead { path: String, error: String },
+    
+    #[error("Failed to parse value '{value}': {error}")]
+    Parse { value: String, error: String },
+    
+    #[error("System command failed: {command}: {error}")]
+    CommandFailed { command: String, error: String },
+    
     #[error("Configuration error: {message}")]
-    ConfigError { message: String },
-
-    #[error("Service not found: {service}")]
-    ServiceNotFound { service: String },
-
-    #[error("Device not found: {device}")]
-    DeviceNotFound { device: String },
-
-    #[error("External dependency error: {dependency} - {message}")]
-    ExternalDependency { dependency: String, message: String },
-}
-
-impl From<std::io::Error> for CollectorError {
-    fn from(err: std::io::Error) -> Self {
-        CollectorError::IoError {
-            message: err.to_string(),
-        }
-    }
-}
-
-impl From<serde_json::Error> for CollectorError {
-    fn from(err: serde_json::Error) -> Self {
-        CollectorError::ParseError {
-            message: err.to_string(),
-        }
-    }
-}
-
-impl From<tokio::time::error::Elapsed> for CollectorError {
-    fn from(_: tokio::time::error::Elapsed) -> Self {
-        CollectorError::Timeout { duration_ms: 0 }
-    }
-}
+    Configuration { message: String },
+    
+    #[error("Metric calculation error: {message}")]
+    Calculation { message: String },
+    
+    #[error("Timeout error: operation took longer than {timeout_ms}ms")]
+    Timeout { timeout_ms: u64 },
+}