fix(gadgets): improve EditFile error message clarity

[zbigniewsobiecki]

Summary

• Changed error header to ERROR: Search content NOT FOUND in file {full path}
• Removed full file content dump from error output to reduce noise
• Keeps suggestions and context when available for debugging

Before

path=src/file.ts status=failed

Error: Search content not found in file

SEARCH CONTENT:
...

CURRENT FILE CONTENT:
[entire file dumped here - noisy!]

After

ERROR: Search content NOT FOUND in file src/file.ts

SEARCH CONTENT:
...

SUGGESTIONS (similar content found):
...

Test plan

• All tests pass (120 tests)
• TypeScript check passes
• Lint passes

🤖 Generated with Claude Code