feat: implement deduplication for browser error logs

[chenjiahan]

Summary

In the previous implementation, we had already prevented the same browser error log from being output consecutively: #6263.

This PR further enhances browser log deduplication by ensuring that identical logs are not repeated within the same build. After a rebuild, these logs can be output again.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[Copilot]

Pull Request Overview

This PR implements enhanced deduplication for browser error logs by tracking reported logs within a build session and preventing duplicate outputs. The enhancement goes beyond the previous consecutive duplicate prevention to eliminate all duplicate logs within the same build cycle.

• Refactors browser log processing to separate formatting from reporting responsibilities
• Adds build-scoped deduplication using a Set to track reported error logs
• Clears the deduplication cache after each build to allow logs to appear again in subsequent builds

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/core/src/server/socketServer.ts	Implements the main deduplication logic with a Set to track reported logs and clears it on build completion
packages/core/src/server/browserLogs.ts	Refactors the error reporting function to only format messages and return strings instead of directly logging
packages/core/src/server/assets-middleware/index.ts	Updates method name from updateStats to onBuildDone to better reflect its purpose
e2e/cases/browser-logs/dedupe-log/src/index.js	Updates test error message format for better test validation
e2e/cases/browser-logs/dedupe-log/index.test.ts	Enhances test to verify deduplication works within builds and logs reappear after rebuilds

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