Add skipContentIdenticalDuplicates flag (default on) for compact baselines

[fornewid]

Summary

Adds an opt-out flag for retaining # duplicate-safe entries in the baseline. Default is true — byte-identical duplicates are dropped from the file so only reviewable entries (# override, # conflict) remain.

Motivation from #39: PR #31 made the # conflict label trustworthy, but the baseline file length did not shrink — in the media3 + exoplayer-ui reproducer 241 of 244 entries simply switched tag. Keeping those lines defeats the point of the baseline. Matches the "compact by default" pattern already established by excludeAndroidXValues = true and the values id-slot skip.

Behavior

• HighlanderCheckTask.processBaseline filters current entries where classification == DUPLICATE_SAFE before override promotion and serialization.
• Scanners still compute byte-hash classification (cost is bounded by duplicate count), so toggling the flag only affects output — not scan semantics.
• Drift detection is preserved both ways: a previously-identical duplicate that diverges later appears as a new # conflict on the next guard run.

API

New public property on HighlanderConfiguration:

public var skipContentIdenticalDuplicates: Boolean = true

highlander/api/highlander.api regenerated.

Closes #39

Migration

Existing 0.0.4 baselines that persist # duplicate-safe entries will diff against scanner output on the first guard run after upgrade — those entries disappear from current so the guard reports them as removed. Re-baseline once:

./gradlew :<project>:highlanderBaseline<Variant>

Users who want to keep historical # duplicate-safe records in the file can set skipContentIdenticalDuplicates = false.

Test plan

• :highlander:test
• :highlander:gradleTest (default-on filter, explicit false retention; prior tests updated to use divergent content where they relied on the old default)
• :highlander:apiCheck
• :sample:app:highlanderBaselineRelease --configuration-cache — sample baseline unchanged (# override drawable/ic_close kept since sample sources have divergent content)

[gemini-code-assist]

Code Review

This pull request introduces the skipContentIdenticalDuplicates configuration property, which defaults to true to omit byte-identical duplicates from baseline files, ensuring they remain compact and focused on actionable conflicts. The implementation includes updates to the Gradle task logic, documentation, and test suite. Review feedback recommends refining the test configurations by removing redundant default property values to enhance readability and maintainability.

[gemini-code-assist]

The test configuration includes properties set to their default values (resources = true, nativeLibs = false). To improve readability and focus on the specific configuration for this test, it's better to only specify non-default values. This makes the test's intent clearer and reduces maintenance if defaults change.

Suggested change

	resources = true
	nativeLibs = false
	assets = false
	skipContentIdenticalDuplicates = false
	assets = false
	skipContentIdenticalDuplicates = false

[gemini-code-assist]

This configuration includes properties set to their default values (resources = true, nativeLibs = false). For better readability and maintainability, please only specify properties that deviate from the default. This highlights the specific setup required for the test.

Suggested change

	resources = true
	nativeLibs = false
	assets = false
	skipContentIdenticalDuplicates = false
	assets = false
	skipContentIdenticalDuplicates = false