Avoid crashing when Shortcuts are using reserved string

[TimoPtr]

Summary

Fix #7270.

Opening the shortcuts settings screen crashed with IndexOutOfBoundsException when the system reported more dynamic shortcuts than the 5 slots the screen manages. The ViewModel mapped the system's dynamic shortcut list positionally into a fixed 6-slot list, and createShortcut treated any ID starting with "shortcut" as dynamic, so a pinned shortcut with a user-typed ID like "shortcutA" was silently registered as an extra dynamic shortcut. Two of those and the screen crashed on every open.

To avoid future problem we forbid the usage of shortcut_x in the ID of pinned shortcut. It comes with a downside that if a dynamic shortcut is moved to a pinned shortcut from the launcher it is going to appear in the list of pinned shortcut to edit but we block it from the UI, the edition is still from the dynamic section.

Step to reproduce the crash, set all the dynamic shortcut and then add a pinned shortcut with an ID that starts with shortcut. This PR is going to avoid the crashes on existing install.

Checklist

• New or updated tests have been added to cover the changes following the testing guidelines.
• The code follows the project's code style and best_practices.
• The changes have been thoroughly tested, and edge cases have been considered.
• Changes are backward compatible whenever feasible. Any breaking changes are documented in the changelog for users and/or in the code for developers depending on the relevance.
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[Copilot]

Pull request overview

Fixes a crash in the legacy “Manage Shortcuts” settings screen by making dynamic shortcut handling slot-aware (by ID) instead of position-based, and by preventing pinned shortcuts from using IDs reserved for dynamic slots.

Changes:

• Map dynamic shortcuts into fixed UI slots using the shortcut ID (shortcut_1..shortcut_5) and ignore extras.
• Add UI validation for pinned shortcut IDs that collide with reserved dynamic IDs.
• Add Robolectric tests covering slot overflow, reserved IDs, and dynamic vs pinned classification.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
common/src/main/res/values/strings.xml	Adds an error message string for reserved pinned shortcut IDs.
app/src/main/kotlin/io/homeassistant/companion/android/settings/shortcuts/legacy/ManageShortcutsViewModel.kt	Reworks dynamic shortcut slot mapping and reserved-ID detection logic.
app/src/main/kotlin/io/homeassistant/companion/android/settings/shortcuts/legacy/views/ManageShortcutsView.kt	Shows/blocks reserved pinned shortcut IDs in the UI.
app/src/test/kotlin/io/homeassistant/companion/android/settings/shortcuts/legacy/ManageShortcutsViewModelTest.kt	Adds Robolectric coverage for the crash scenario and ID classification.