fix: Inline recording-delete confirm + stable redirects

- Replace native confirm() in the recording list with an inline
  two-step confirm row; hide the player via visibility:hidden
  while open so the row height stays stable.
- Hard-redirect recording delete back to /web/cases/{id}/recordings
  instead of relying on the Referer header (which silently fell
  back to /web/cases when stripped).
- Switch analyze/reset to a hidden return_to form field so the
  source page (case detail vs. case list) is preserved reliably,
  with same-origin /web/ prefix validation.
- Tighten delete_recording_test on the concrete Location header;
  adjust analyze/reset redirect expectations to the new
  case-detail fallback.

server/tests/delete_recording_test.rs

@@ -54,6 +54,14 @@ async fn delete_recording_removes_file_and_sidecars_and_invalidates_derived() {
         "delete should redirect (3xx), got {}",
         resp.status()
     );
+    let expected_location = format!("/web/cases/{case_id}/recordings");
+    assert_eq!(
+        resp.headers()
+            .get(axum::http::header::LOCATION)
+            .and_then(|v| v.to_str().ok()),
+        Some(expected_location.as_str()),
+        "delete should redirect back to the recording list, not the case list"
+    );
 
     // Victim + its sidecars are gone.
     assert!(!case_dir.join(&victim).exists(), "m4a should be deleted");
@@ -212,6 +220,14 @@ async fn delete_last_recording_clears_case() {
         "last-recording delete should still redirect, got {}",
         resp.status()
     );
+    let expected_location = format!("/web/cases/{case_id}/recordings");
+    assert_eq!(
+        resp.headers()
+            .get(axum::http::header::LOCATION)
+            .and_then(|v| v.to_str().ok()),
+        Some(expected_location.as_str()),
+        "last-recording delete should still redirect to the recording list"
+    );
 
     assert!(!case_dir.join(&only).exists());
     assert!(!case_dir.join(ONELINER_FILENAME).exists());