feat: Editing nested fragments (dialogs inside dialog, dialogs inside studio component)

[ruchamahabal]

• Before this, editing nested overlays was not easily possible. If you added SettingsDialog, it opened a fragment, and if you dropped another dialog inside SettingsDialog, it opened a dialog fragment. Once you saved the last dialog, you only had an option to go back to the main page, not the parent (Settings Dialog). You would have to do this via the Layers panel again. Now nested overlays show up in the breadcrumbs.
• Also, there was no way to go to an overlay component from the canvas since they don't render inline. You had to find the overlay component in the Layers panel and then click on it to edit it. Now the list of overlay elements is shown below the canvas, so you can quickly navigate from here to edit them. This includes overlay blocks + overlay blocks saved as studio components
• Dirty state tracking is also added for the fragment canvas.

nested-overlays.mp4

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To edit a studio component, you had to right-click> Edit Component. Now there are more shortcuts for this action

Fixes:

• pass a block copy to fragment save actions so a saved fragment isn't re-marked dirty

• props panel no longer writes component defaults into the block on selection
  this was marking canvas dirty on some block selection that didn't change, prop editor panel was setting default on the component block directly. Component already applies its own defaults at render time, so just show them in props panel, don't directly apply

[greptile-apps]

Confidence Score: 4/5

The PR is not yet safe to merge because a pending save can still close or clean the wrong fragment after concurrent navigation.

Fragment identity is not captured before awaiting the save, while breadcrumb and nested-editor actions can mutate the stack during that wait.

Files Needing Attention: frontend/src/pages/StudioPage.vue

_{Reviews (12): Last reviewed commit: "fix: props panel no longer writes compon..." | Re-trigger Greptile}