fix: evaluation detail type should be optional

[joker23]

• Updates the common client typing so evaluation detail properties are optional (better compat)
• Removes the browser sdk compat module
• Moved the non-optional evaluation detail type to RN only (to avoid breaking changes)

---

Note

Aligns evaluation detail typings and removes deprecated browser compat code.

• Types: Make reason optional in LDEvaluationDetail and LDEvaluationDetailTyped in shared/sdk-client for better compatibility
• React Native: Add RN-specific LDEvaluationDetail/LDEvaluationDetailTyped (nullable reason) and re-export; update useTypedVariationDetail to use these types
• Browser SDK: Remove the entire src/compat module, related tests, export entries, and build entry; delete upgrade docs; simplify package.json exports and tsup config

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[github-actions]

@launchdarkly/js-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25394 bytes
Compressed size limit: 26000
Uncompressed size: 124693 bytes

[github-actions]

@launchdarkly/browser size report
This is the brotli compressed size of the ESM build.
Compressed size: 171362 bytes
Compressed size limit: 200000
Uncompressed size: 798447 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 19354 bytes
Compressed size limit: 20000
Uncompressed size: 99752 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 23335 bytes
Compressed size limit: 25000
Uncompressed size: 81335 bytes