fix(harness): make sandbox file tools image-compatible

[logicwu0]

Summary

• avoid nested command substitution when creating parent directories for sandbox writes and uploads
• preserve shell error details from write failures
• perform exact edit replacements through the filesystem transfer APIs instead of requiring Python in the sandbox image
• update sandbox image requirements and add regression coverage

Testing

• mvn -pl agentscope-harness -Dtest=BaseSandboxFilesystemTest,SandboxBackedFilesystemTest,ProjectAwareOverlayTest,LocalFilesystemModeTest test
• git diff --check

Fixes #2365

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!