feat: add custom sleep timer picker (#2206)

## Summary

* **What is the goal of this PR?**
Mainly fixes #2196, but also allows users to set a sleep time of 1~30
min or to never sleep.

* **What changes are included?**

1. Revert changes from #1948 and #2137 (Sorry @Uri-Tauber)
2. Cherrypick changes from
https://github.com/uxjulia/CrossInk/commit/0cb91c3dd1c63f0559d4392fadc4a8340af5bdde
and
https://github.com/uxjulia/CrossInk/commit/4e6bd634b6ede51ff1a7107ba3e8efcd152bc6ee
for a timeout interval picker UI, the custom sleep time feature, and
migrate the existing setting in v1.3.0, `sleepTimeout`, to
`sleepTimeoutMinutes` (Thanks! @uxjulia)
3. Add a "Never" at the far right of the timeout interval picker

---

### AI Usage

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please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**PARTIALLY**_

---------

Co-authored-by: Julia <julia@uxj.io>

lib/I18n/translations/valencian.yaml

@@ -85,6 +85,9 @@ STR_SCREEN_MARGIN: "Marge de pantalla del lector"
 STR_PARA_ALIGNMENT: "Alineació de paràgrafs del lector"
 STR_HYPHENATION: "Partició de mots"
 STR_TIME_TO_SLEEP: "Temps per entrar en repòs"
+STR_SLEEP_TIMER_VALUE_FORMAT: "%u min"
+STR_SLEEP_NEVER: "Mai"
+STR_SLEEP_TIMER_STEP_HINT: "Esquerra/Dreta: 1 min  Amunt/Avall: 5 min"
 STR_SHOW_HIDDEN_FILES: "Mostra arxius ocults"
 STR_REMOVE_READ_FROM_RECENTS: "Esborra els llibres llegits de la llista de recents"
 STR_MOVE_FINISHED_TO_READ: "Mou els llibres acabats a la carpeta Read"
@@ -155,7 +158,6 @@ STR_ALIGN_LEFT: "Esquerra"
 STR_CENTER: "Centre"
 STR_ALIGN_RIGHT: "Dreta"
 STR_MIN_1: "1 min"
-STR_MIN_3: "3 min"
 STR_MIN_5: "5 min"
 STR_MIN_10: "10 min"
 STR_MIN_15: "15 min"