feat(snapshot): Merge snapshot extension into main sentry DSL

[runningcode]

Summary

• Moves snapshot configuration from the standalone sentrySnapshot plugin into the main sentry { snapshots { } } extension
• Auto-detects Paparazzi plugin for test generation wiring (no enabled flag needed)
• Wires sentryUploadSnapshots task to Paparazzi output directory and ordering
• Uses consistent plural "snapshots" naming throughout
• Upload tasks remain registered for all variants (library-agnostic), test generation is Paparazzi-specific

DSL before

// Separate plugin required
plugins { id("io.sentry.android.snapshot") }

sentrySnapshot {
    includePrivatePreviews = true
    packageTrees = listOf("com.example.app")
    theme = "MyTheme"
}

DSL after

sentry {
    snapshots {
        includePrivatePreviews = true
        packageTrees = listOf("com.example.app")
        theme = "MyTheme"
    }
}

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Semver Impact of This PR

🟡 Minor (new features)

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[romtsn]

LGTM, but I guess I'd still prefer to have an enabled flag -- in case something goes off with the snapshots' tasks, people that don't use snapshots could simply disable the feature. Because now we're configuring those tasks unconditionally, right (even though they don't execute without the paparazzi plugin applied)?

[runningcode]

Actually, that's a really good point. I built it so that all the tasks are only registered and not dependencies of other tasks unless you have the paparazzi plugin applied.
The issue is that some people might already be using paparazzi so having this auto-apply is a bad idea. Thank you! i've updated it

[sentry]

Bug: The code unsafely calls .first() to find a "snapshots" directory, which will crash the build if the directory is not found.
_{Severity: MEDIUM}

Suggested Fix

Replace the call to .first() with a safer alternative like .firstOrNull(). If the result is null (meaning the directory was not found), you should handle it gracefully, for example by logging a warning or skipping the task's operation, to prevent the build from crashing.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location:
plugin-build/src/main/kotlin/io/sentry/android/gradle/AndroidComponentsConfig.kt#L495-L497

Potential issue: The code at line 526 calls `.first()` on a collection of files to find
one named "snapshots". If the Paparazzi test task runs but does not produce a
"snapshots" output directory for any reason, this call will throw a
`NoSuchElementException` during Gradle's execution phase, causing the build to fail.
This can happen if the Paparazzi configuration is altered or if it behaves unexpectedly
for a specific variant.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 2 total unresolved issues (including 1 from previous review).

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

[sentry]

Bug: The SentryUploadSnapshotsTask is registered unconditionally but its required snapshotsPath property is not set if the Paparazzi plugin is missing or if unit tests are disabled for a variant, causing a build failure.
_{Severity: HIGH}

Suggested Fix

Move the registration of SentryUploadSnapshotsTask inside the project.pluginManager.withPlugin("app.cash.paparazzi") block. This ensures the task is only created when its required snapshotsPath property can be correctly configured, preventing build failures when Paparazzi is not in use.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location:
plugin-build/src/main/kotlin/io/sentry/android/gradle/AndroidComponentsConfig.kt#L523-L524

Potential issue: The `SentryUploadSnapshotsTask` is registered if
`extension.snapshots.enabled` is true. However, its required `snapshotsPath` property is
only configured under specific conditions. This leads to build failures in two
scenarios: 1) When the Paparazzi plugin is not applied, the configuration block is
skipped, leaving `snapshotsPath` unassigned. 2) When the Paparazzi plugin is applied but
unit tests are disabled for a specific build variant (e.g., `release`), an early return
in an `afterEvaluate` block prevents `snapshotsPath` from being set for that variant's
task. In both cases, Gradle's task validation fails because a required property is
missing.