Clarify the Copilot PR-review prompt to execute five explicit phases (Understanding, Test Review, Fix Exploration, Alternative Comparison, Final Review). Add a new pipeline step that invokes a Copilot "post-comment" skill, captures its exit code, logs output to $(Build.ArtifactStagingDirectory)/copilot-logs, and sets a PostCommentFailed variable on failure. Ensure artifacts dir exists, surface warnings on failure, and make the original post-comment fallback step run only when the skill step failed. Update step display names and preserve artifact publishing.

Add a pipeline step (Cache Prompt File) that loads eng/pipelines/prompts/pr-review-prompt.md and copies it to /tmp/copilot-prompts/pr-review-prompt.md before the PR branch checkout. Update the later Copilot step to read the prompt from the cached location and adjust the error message. This prevents failures when the prompt file is absent on the PR branch by ensuring a stable copy is available for the review step.

Replace brittle iPhone Xs + iOS 18.5 lookup with a prioritized selection routine. The script now iterates preferred iOS versions and device models, picks the first available preferred device or falls back to the first available iPhone, and finally falls back to any available simulator. It also surfaces runtime info when listing available simulators and reports the selected device name and UDID before booting.

Replace direct checkout of the PR branch with logic that fetches the PR, computes the merge-base against the current branch, and cherry-picks commits from the merge-base..PR_HEAD onto the current branch (using --no-commit). Adds commit counting, a warning when no commits are found, conflict handling with status and diff output, and extra logging (current branch, merge base, commit count, last commit and status). Also updates the pipeline step display name to 'Cherry-pick PR Changes' and tweaks the fetch message.

Add a CI step to run ./build.ps1 --target=dotnet-buildtasks (Release, diagnostic) to compile MSBuild tasks required for MAUI builds. The step includes a retry on failure and sets DOTNET_TOKEN and PRIVATE_BUILD environment variables for accessing internal artifacts. Placed before the simulator/emulator listing to ensure tasks are available for subsequent MAUI jobs.

Add provisioning steps to eng/pipelines/common/provision.yml to create an iPhone Xs simulator with iOS 18.5 (falling back to iOS 18.x if 18.5 is not available). The script finds the appropriate runtime and device type, checks for an existing simulator to avoid duplicates, attempts creation if missing, and prints available iPhone simulators. This ensures the required simulator is present for UI tests and logs useful diagnostics if runtimes or device types are not available.

<!-- Please let the below note in for people that find this PR -->
> [!NOTE]
> Are you waiting for the changes in this PR to be merged?
> It would be very helpful if you could [test the resulting
artifacts](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from
this PR and let us know in a comment if this change resolves your issue.
Thank you!

## Description

Removes the dead `OnlyAndroid` method from `BaseTemplateTests` and its 3
call sites in `AOTTemplateTest` and `SimpleTemplateTest`.

### Why this is dead code

`OnlyAndroid` calls `ReplaceInFile` searching for:
```
<TargetFrameworks>net10.0-android;net10.0-ios;net10.0-maccatalyst</TargetFrameworks>
```

But MAUI templates now use MSBuild conditions with `DOTNET_TFM-android`
placeholders — the static string above no longer exists in generated
projects. The method is a silent no-op on every call.

### Why remove it now

On `net11.0`, this method was already removed by PR #33576. When merging
`main → net11.0`, the call sites in `AOTTemplateTest.cs` (added by PR
#33756) cause CS0103 build errors since the method does not exist on
`net11.0`. Removing it from `main` prevents these merge conflicts going
forward.

### Changes

- **`BaseTemplateTests.cs`**: Removed `OnlyAndroid` method definition
- **`AOTTemplateTest.cs`**: Removed 2 call sites (`PublishNativeAOT`,
`PublishNativeAOTRootAllMauiAssemblies`)
- **`SimpleTemplateTest.cs`**: Removed 1 call site (`Build`)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Reset patterns:
- global.json
- NuGet.config
- eng/Version.Details.xml
- eng/Versions.props
- eng/common/*

# Conflicts:
#	src/Controls/src/Core/PublicAPI/net-android/PublicAPI.Unshipped.txt
#	src/Controls/src/Core/PublicAPI/net-ios/PublicAPI.Unshipped.txt
#	src/Controls/src/Core/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt
#	src/Controls/src/Core/PublicAPI/net-tizen/PublicAPI.Unshipped.txt
#	src/Controls/src/Core/PublicAPI/net-windows/PublicAPI.Unshipped.txt
#	src/Controls/src/Core/PublicAPI/net/PublicAPI.Unshipped.txt
#	src/Controls/src/Core/PublicAPI/netstandard/PublicAPI.Unshipped.txt

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>