bug+feature: Lockscreen blur bugfix + add support for transition

[engel-lucas]

BUG:

On the lockscreen, when switching between clock and login prompt, the blur and brightness did not change to gnome defaults but stayed at the values set by the extension. (I tried several settings for blur and brightness, including all the presets.)

Step by step:

• enable dynamic lockscreen blur
• restart gnome-shell (alt+f2, r, enter)
• lock screen (super+L, or via top bar settings)
• scroll down (reveals login prompt)
  Expect blur to change in last step, but doesn't.

BUGFIX: first commit

In journal, I saw that Blur._disable() is called when locking, and Blur._enable() when unlocking the screen. To prevent this disabling of the extension on the lockscreen, I added "session-modes": ["user", "unlock-dialog"] to metadata.json.

FEATURE: second commit

changed setTransitionProgress to also update blur and brightness in the transition animation.
this may require further testing on other OS/Gnome versions.

everything done (and only tested) on

• Ubuntu 24.04
• Gnome 46.0
• Extension commit 074cda6

[neffo]

Thanks, just switched this to point to v52 branch.

Sorry I didn't have enough time to test this for introduction in v51.

[neffo]

Can we detect the current session mode? Ideally we'd want to disable the main extension during lockscreen and only enable the blur component.