When restrict_to_workspace is true, guardCommand now properly skips
URL paths like 'wttr.in/Beijing' in curl commands. Previously, these
were incorrectly matched as relative paths and blocked.

Issue: sipeed#1042

Add isBinaryFile function to detect binary files (PDF, images, videos, etc.)
by checking the ratio of non-printable characters in the first 512 bytes.
When a binary file is detected, return an error message instead of
returning garbled content.

Fixes: sipeed#1049

Previously, the session flag was ignored in the agent command, with custom session keys
being replaced by the default routing session. The issue was caused by the code only
honoring session keys that started with the prefix 'agent:'.

This fix modifies the condition on how the session key is selected to honor any custom
session key provided via command line --session flag, regardless of prefix. Now the
custom session keys like "foobar" will generate "foobar.json" file instead of
"agent_main_main.json".

FIXES sipeed#1039

🤖 AI Assisted - Human designed the solution, AI helped implement it

Add test case verifying that read_file tool properly detects and rejects binary files such as PDFs with appropriate error message, preventing the generation of large amounts of garbage characters.