Refactor IPC and DTO structures; remove unused code and streamline message handling

- Removed unused structs and methods from `response.rs`, `usage.rs`, and `client.rs`.
- Simplified `Connection` handling in `conn.rs` to only support Unix sockets.
- Updated `IpcServer` to exclusively use Unix sockets and removed TCP handling.
- Cleaned up `editlog.rs` by removing loading and recent entry methods.
- Refactored `memory.rs` to eliminate unused functions related to lesson promotion and retrospective creation.
- Enhanced `search.rs` to support multiple search providers and improved error handling.
- Updated chat view logic to simplify message display and improve user experience.
- Removed deprecated modules and constants from various files to streamline the codebase.

src/model/editlog.rs

@@ -40,24 +40,6 @@ impl EditLog {
         Ok(())
     }
 
-    pub fn load(path: &std::path::Path) -> std::io::Result<Self> {
-        let content = std::fs::read_to_string(path)?;
-        let entries: Vec<EditLogEntry> = content
-            .lines()
-            .filter_map(|l| serde_json::from_str(l).ok())
-            .collect();
-        Ok(EditLog {
-            entries,
-            path: path.to_path_buf(),
-        })
-    }
-
-    pub fn recent(&self, n: usize) -> &[EditLogEntry] {
-        let len = self.entries.len();
-        let start = len.saturating_sub(n);
-        &self.entries[start..]
-    }
-
     pub fn len(&self) -> usize {
         self.entries.len()
     }
@@ -73,7 +55,6 @@ mod tests {
         let _ = std::fs::create_dir_all(&dir);
         let log = EditLog::new(&dir);
         assert_eq!(log.len(), 0);
-        assert_eq!(log.recent(5).len(), 0);
         let _ = std::fs::remove_dir_all(&dir);
     }
 
@@ -94,19 +75,10 @@ mod tests {
         };
         log.append(entry.clone()).unwrap();
         assert_eq!(log.len(), 1);
-
-        let loaded = EditLog::load(&log.path).unwrap();
-        assert_eq!(loaded.len(), 1);
-        assert_eq!(loaded.entries[0].reason, "test reason");
-        assert_eq!(loaded.entries[0].tool, "write");
-        assert_eq!(loaded.entries[0].path, "test.txt");
-
-        let recent = log.recent(1);
-        assert_eq!(recent.len(), 1);
-        assert_eq!(recent[0].bytes_delta, 42);
-
-        let empty = log.recent(0);
-        assert_eq!(empty.len(), 0);
+        assert_eq!(log.entries[0].reason, "test reason");
+        assert_eq!(log.entries[0].tool, "write");
+        assert_eq!(log.entries[0].path, "test.txt");
+        assert_eq!(log.entries[0].bytes_delta, 42);
         let _ = std::fs::remove_dir_all(&dir);
     }
 
@@ -128,10 +100,8 @@ mod tests {
             }).unwrap();
         }
         assert_eq!(log.len(), 5);
-        let recent = log.recent(3);
-        assert_eq!(recent.len(), 3);
-        assert_eq!(recent[0].reason, "reason 2");
-        assert_eq!(recent[2].reason, "reason 4");
+        assert_eq!(log.entries[0].reason, "reason 0");
+        assert_eq!(log.entries[4].reason, "reason 4");
         let _ = std::fs::remove_dir_all(&dir);
     }
 }