Remove legacy logs/ directory, consolidate all data under .g3/

This change removes the legacy logs/ directory and consolidates all
session data, error logs, and discovery files under the .g3/ directory.

New directory structure:
- .g3/sessions/<session_id>/session.json - session logs
- .g3/errors/ - error logs (was logs/errors/)
- .g3/background_processes/ - background process logs
- .g3/discovery/ - planner discovery files (was workspace/logs/)

Changes:
- paths.rs: Remove get_logs_dir()/logs_dir(), add get_errors_dir(),
  get_background_processes_dir(), get_discovery_dir()
- session.rs: Anonymous sessions now use .g3/sessions/anonymous_<ts>/
- error_handling.rs: Errors now saved to .g3/errors/
- project.rs: Remove logs_dir() and ensure_logs_dir() methods
- feedback_extraction.rs: Remove logs_dir field and fallback logic
- planner: Use .g3/ for workspace data and .g3/discovery/ for reports
- flock.rs: Look for session metrics in .g3/sessions/
- coach_feedback.rs: Remove fallback to logs/ path
- Update all tests to use new paths
- Update README.md and .gitignore

crates/g3-core/src/feedback_extraction.rs

@@ -8,10 +8,9 @@
 //!
 //! Used by both autonomous mode (g3-cli) and planning mode (g3-planner).
 
-use crate::{logs_dir, Agent, TaskResult};
+use crate::{Agent, TaskResult};
 use crate::ui_writer::UiWriter;
 use serde_json::Value;
-use std::path::PathBuf;
 use tracing::{debug, warn};
 
 /// Result of feedback extraction with source information
@@ -60,8 +59,6 @@ impl ExtractedFeedback {
 pub struct FeedbackExtractionConfig {
     /// Whether to print debug information
     pub verbose: bool,
-    /// Custom logs directory (overrides default)
-    pub logs_dir: Option<PathBuf>,
     /// Default feedback message if extraction fails
     pub default_feedback: String,
 }
@@ -70,7 +67,6 @@ impl Default for FeedbackExtractionConfig {
     fn default() -> Self {
         Self {
             verbose: false,
-            logs_dir: None,
             default_feedback: "The implementation needs review. Please ensure all requirements are met and the code compiles without errors.".to_string(),
         }
     }
@@ -149,17 +145,10 @@ fn try_extract_last_assistant_message(
     session_id: &str,
     config: &FeedbackExtractionConfig,
 ) -> Option<String> {
-    // Try new .g3/sessions/<session_id>/session.json path first
-    let log_file_path = crate::get_session_file(session_id);
+    let _ = config; // config no longer used but kept for API compatibility
     
-    // Fall back to old logs/ path if new path doesn't exist
-    let log_file_path = if log_file_path.exists() {
-        log_file_path
-    } else {
-        let logs_path = config.logs_dir.clone().unwrap_or_else(logs_dir);
-        logs_path.join(format!("g3_session_{}.json", session_id))
-    };
-
+    // Use .g3/sessions/<session_id>/session.json path
+    let log_file_path = crate::get_session_file(session_id);
     if !log_file_path.exists() {
         debug!("Session log file not found: {:?}", log_file_path);
         return None;
@@ -214,17 +203,10 @@ fn try_extract_from_session_log(
     session_id: &str,
     config: &FeedbackExtractionConfig,
 ) -> Option<String> {
-    // Try new .g3/sessions/<session_id>/session.json path first
-    let log_file_path = crate::get_session_file(session_id);
+    let _ = config; // config no longer used but kept for API compatibility
     
-    // Fall back to old logs/ path if new path doesn't exist
-    let log_file_path = if log_file_path.exists() {
-        log_file_path
-    } else {
-        let logs_path = config.logs_dir.clone().unwrap_or_else(logs_dir);
-        logs_path.join(format!("g3_session_{}.json", session_id))
-    };
-
+    // Use .g3/sessions/<session_id>/session.json path
+    let log_file_path = crate::get_session_file(session_id);
     if !log_file_path.exists() {
         debug!("Session log file not found: {:?}", log_file_path);
         return None;
@@ -358,17 +340,10 @@ fn try_extract_from_conversation_history(
     session_id: &str,
     config: &FeedbackExtractionConfig,
 ) -> Option<String> {
-    // Try new .g3/sessions/<session_id>/session.json path first
-    let log_file_path = crate::get_session_file(session_id);
+    let _ = config; // config no longer used but kept for API compatibility
     
-    // Fall back to old logs/ path if new path doesn't exist
-    let log_file_path = if log_file_path.exists() {
-        log_file_path
-    } else {
-        let logs_path = config.logs_dir.clone().unwrap_or_else(logs_dir);
-        logs_path.join(format!("g3_session_{}.json", session_id))
-    };
-
+    // Use .g3/sessions/<session_id>/session.json path
+    let log_file_path = crate::get_session_file(session_id);
     if !log_file_path.exists() {
         return None;
     }
@@ -652,7 +627,6 @@ mod tests {
     fn test_feedback_extraction_config_default() {
         let config = FeedbackExtractionConfig::default();
         assert!(!config.verbose);
-        assert!(config.logs_dir.is_none());
         assert!(config.default_feedback.contains("review"));
     }
 }