feat: add session deletion with per-provider cleanup and path safety

Add delete_session Tauri command dispatching to provider-specific deletion
logic for all 5 providers (Claude, Codex, Gemini, OpenCode, OpenClaw).
Includes path traversal protection via canonicalize + starts_with validation,
session ID verification against file contents, frontend confirmation dialog
with optimistic cache updates, i18n keys (zh/en/ja), and component tests.

src-tauri/src/session_manager/providers/codex.rs

@@ -81,6 +81,27 @@ pub fn load_messages(path: &Path) -> Result<Vec<SessionMessage>, String> {
     Ok(messages)
 }
 
+pub fn delete_session(_root: &Path, path: &Path, session_id: &str) -> Result<bool, String> {
+    let meta = parse_session(path)
+        .ok_or_else(|| format!("Failed to parse Codex session metadata: {}", path.display()))?;
+
+    if meta.session_id != session_id {
+        return Err(format!(
+            "Codex session ID mismatch: expected {session_id}, found {}",
+            meta.session_id
+        ));
+    }
+
+    std::fs::remove_file(path).map_err(|e| {
+        format!(
+            "Failed to delete Codex session file {}: {e}",
+            path.display()
+        )
+    })?;
+
+    Ok(true)
+}
+
 fn parse_session(path: &Path) -> Option<SessionMeta> {
     let (head, tail) = read_head_tail_lines(path, 10, 30).ok()?;
 
@@ -192,3 +213,30 @@ fn collect_jsonl_files(root: &Path, files: &mut Vec<PathBuf>) {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    #[test]
+    fn delete_session_removes_jsonl_file() {
+        let temp = tempdir().expect("tempdir");
+        let path = temp
+            .path()
+            .join("rollout-2026-03-06T21-50-12-019cc369-bd7c-7891-b371-7b20b4fe0b18.jsonl");
+        std::fs::write(
+            &path,
+            concat!(
+                "{\"timestamp\":\"2026-03-06T21:50:12Z\",\"type\":\"session_meta\",\"payload\":{\"id\":\"019cc369-bd7c-7891-b371-7b20b4fe0b18\",\"cwd\":\"/tmp/project\"}}\n",
+                "{\"timestamp\":\"2026-03-06T21:50:13Z\",\"type\":\"response_item\",\"payload\":{\"type\":\"message\",\"role\":\"user\",\"content\":\"hello\"}}\n"
+            ),
+        )
+        .expect("write session");
+
+        delete_session(temp.path(), &path, "019cc369-bd7c-7891-b371-7b20b4fe0b18")
+            .expect("delete session");
+
+        assert!(!path.exists());
+    }
+}