fix: Filter out edit events from search result context

[shinaoka]

PR: Filter out edit events from search result context

Summary

When searching for text that matches an edited message, the search result context (events_before / events_after) may include previous edit events of the same message. These appear as confusing "previous messages" when they're actually just edit history.

For example, if a message was edited: AAAAAA → BBBBBB → CCCCCCC, searching for "CCCCCCC" might show "BBBBBB" as a previous message, which is misleading.

Changes

• Filter out m.replace events from events_before and events_after in local search results
• Add unit tests for the filtering logic

Files Changed

• src/Searching.ts - Add filter for edit events in context
• test/unit-tests/Searching-test.ts - Add tests

Tests

Unit tests added in test/unit-tests/Searching-test.ts:

• filters out edit events (m.replace) from context events - Verifies that edit events are removed from events_before and events_after, while regular messages are preserved
• preserves non-edit events in context - Verifies that non-edit events remain in context unchanged

Technical Details

Edit events are identified by checking content["m.relates_to"].rel_type === "m.replace".

Checklist

• I have read through review guidelines and CONTRIBUTING.md.
• Tests written for new code (and old code if feasible).
• New or updated public/exported symbols have accurate TSDoc documentation.
• Linter and other CI checks pass.
• I have licensed the changes to Element by completing the Contributor License Agreement (CLA)