feat: add DeviceUIConfig.screen_rotation

[attakygit]

What does this PR do?

Adds a persisted screen rotation to DeviceUIConfig so the color UI can offer
orientation as a runtime setting instead of a build-time choice.

Today a device that can render both the 320x240 and the 240x320 layout has to
pick one at compile time via VIEW_320x240 / VIEW_240x320. There is nowhere
to store a user's choice, so the only way to change orientation is to reflash.

The device-ui side that consumes this field is implemented and hardware-tested;
see the companion PR linked below.

The field

ScreenRotation screen_rotation = 20;

enum ScreenRotation {
  ROTATION_0   = 0;
  ROTATION_90  = 1;
  ROTATION_180 = 2;
  ROTATION_270 = 3;
}

Quarter turns relative to the device's built-in display orientation, not
absolute panel rotations.

• ROTATION_0 is the existing behaviour. Every device that never sets this
  field keeps rendering exactly as it does today, and the default value of an
  unset proto3 enum is 0, so no migration is involved.
• The 0..3 quarter-turn numbering matches LVGL's LV_DISPLAY_ROTATION_* and the
  masking already used for MESHTASTIC_FB_ROTATION in device-ui Deprecate MyNodeInfo fields: max_channels, message_timeout_msec, has_wifi, channel_utilization, and air_util_tx #355 — same
  concept, same numbering, different transport.
• It is read at boot. Changing it needs a restart, because an LVGL layout tree
  cannot be rebuilt in place once the view has cached its object pointers. The
  comment says so.

Why in the proto rather than firmware-side

Open question for you, and I'm happy either way:

DeviceUIConfig is where every other persisted MUI setting already lives
(brightness, theme, language, touch calibration), and it reaches the firmware
through the existing storeUIConfig path, so device-ui needs no new plumbing
and the phone app could surface it later.

The alternative is a firmware-owned byte with device-ui exposing a small
load/store hook. That avoids touching the wire format entirely, at the cost of a
private file, no app visibility, and a GIT_TAG/submodule bump chain to get the
generated bindings anywhere.

If you'd rather not spend a field number on this, say so and I'll redo it the
firmware-owned way — the device-ui implementation is unaffected apart from where
it reads and writes the value.

Checklist

• All top level messages commented (no new messages)
• All enum members have unique descriptions
• buf format clean

Companion PR

device-ui implementation: meshtastic/device-ui#359

Summary by CodeRabbit

• New Features
  • Added support for selecting color UI screen rotation: 0°, 90°, 180°, or 270°.
  • Device display orientation can now be configured through device settings.

[CLAassistant]

All committers have signed the CLA.

[coderabbitai]

📝 Walkthrough

Walkthrough

The device UI protobuf now supports color UI screen rotation. The configuration includes a screen_rotation field, and the ScreenRotation enum defines 0°, 90°, 180°, and 270° orientations.

Changes

Screen rotation configuration

Layer / File(s)	Summary
Rotation configuration contract meshtastic/device_ui.proto	DeviceUIConfig now includes screen_rotation. The new ScreenRotation enum defines four quarter-turn orientations. The setting applies after restart.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely identifies the main change: adding DeviceUIConfig.screen_rotation.
Description check	✅ Passed	The description explains the change, rationale, behavior, compatibility, testing, checklist status, and companion PR.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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