fix(core): defer output rearrangement to fix VT switch issues

[glyvut]

Add a single-shot timer in RootSurfaceContainer to batch surface output updates. This fixes the issue where windows could not be dragged after VT switch by ensuring proper output recovery sequence.

在RootSurfaceContainer中添加单次定时器合并表面输出更新，
修复VT切换后窗口无法拖动等问题。

Log: 修复VT切换后窗口无法拖动的bug
PMS: BUG-366537
Influence: 切换VT后窗口可正常拖动，多显示器恢复更平滑

Summary by Sourcery

Defer surface-output rearrangement in the root surface container to batch output updates and improve output recovery after VT switches.

Bug Fixes:

• Fix window drag failures and related focus issues after VT switches by ensuring outputs and surface ownership are updated in the correct sequence.

Enhancements:

• Batch surface-output updates using a single-shot timer in the root surface container to make multi-display configuration changes and recovery smoother.

[sourcery-ai]

Reviewer's Guide

Adds a deferred, single-shot QTimer-based batching mechanism in RootSurfaceContainer to regroup surface-output rearrangement after output add/remove events, fixing VT switch drag issues and smoothing multi-display recovery.

Sequence diagram for deferred surface-output rearrangement with QTimer

sequenceDiagram
    participant RootSurfaceContainer
    participant QTimer
    participant Workspace

    RootSurfaceContainer->>QTimer: start(0)  Note left of RootSurfaceContainer: addOutput/removeOutput
    QTimer-->>QTimer: timeout (singleShot)
    QTimer->>RootSurfaceContainer: [lambda connected to timeout]
    loop for each surface in surfaces()
        RootSurfaceContainer->>RootSurfaceContainer: updateSurfaceOutputs(surface)
    end
    RootSurfaceContainer->>Workspace: updateSurfacesOwnsOutput()

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File-Level Changes

Change	Details	Files
Introduce a single-shot QTimer in RootSurfaceContainer to batch output rearrangement after display topology changes.	Add QTimer forward declaration in the header and a QTimer* member m_outputRearrangeTimer to RootSurfaceContainer. Instantiate m_outputRearrangeTimer in the RootSurfaceContainer constructor with this as parent and configure it as single-shot. Connect the timer's timeout to iterate all current surfaces, calling updateSurfaceOutputs(surface) for each, then trigger workspace()->updateSurfacesOwnsOutput() if a workspace exists. On addOutput and removeOutput, start the timer with 0ms delay to defer and coalesce rearrangement work across multiple output changes.	src/core/rootsurfacecontainer.cpp src/core/rootsurfacecontainer.h

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[sourcery-ai]

Hey - I've left some high level feedback:

• The lambda connected to m_outputRearrangeTimer->timeout duplicates logic that might be reused elsewhere; consider extracting it into a dedicated private method (e.g. rearrangeOutputs()) and calling that from both the timer and any future callers for clarity and easier maintenance.
• Instead of calling m_outputRearrangeTimer->start(0) in multiple places, a small helper like scheduleOutputRearrange() would centralize the batching behavior (including any future changes to delay or conditions) and make the intent of the 0ms single-shot timer more self-documenting.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The lambda connected to `m_outputRearrangeTimer->timeout` duplicates logic that might be reused elsewhere; consider extracting it into a dedicated private method (e.g. `rearrangeOutputs()`) and calling that from both the timer and any future callers for clarity and easier maintenance.
- Instead of calling `m_outputRearrangeTimer->start(0)` in multiple places, a small helper like `scheduleOutputRearrange()` would centralize the batching behavior (including any future changes to delay or conditions) and make the intent of the 0ms single-shot timer more self-documenting.

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: glyvut

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