Fix sprint tracking: Story 3.1 was already implemented

- Updated sprint-status.yaml: 3-1-save-and-load-scene-presets → done
- Updated Story 3.1 file header: Status → done
- Updated last_updated timestamp

Note: Story 3.1 (Save & Load Scene Presets) was implemented as part of
commit a1e8886 (Story 3.2 done) which created ScenePresetManager,
PresetSaveDialog, PresetLoadDialog, and related tests.

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

_bmad-output/implementation-artifacts/sprint-status.yaml

@@ -35,7 +35,7 @@
 # - Dev moves story to 'review', then runs code-review (fresh context, different LLM recommended)
 
 generated: "2026-05-21T01:00:00+02:00"
-last_updated: "2026-05-24T18:58:00+02:00"
+last_updated: "2026-05-24T19:00:00+02:00"
 project: video-view-manager
 project_key: NOKEY
 tracking_system: file-system
@@ -61,7 +61,7 @@ development_status:
 
   # Epic 3: Scene-Aware Camera Automation (Scene Presets)
   epic-3: in-progress
-  3-1-save-and-load-scene-presets: ready-for-dev
+  3-1-save-and-load-scene-presets: done
   3-2-scene-auto-apply-and-confirmationbar: done
   3-3-preset-import-and-export: done
   epic-3-retrospective: optional