Fix Copilot chatSessions shell-command and prompt extraction

What happened

• The Copilot modern chatSessions parser was dropping shell tool commands and the original prompt metadata.
• It normalized toolCallRounds[].toolCalls[] names, but it always emitted bashCommands: [] and left userMessage empty.
• This caused VS Code Copilot sessions to undercount shell activity and lose the actual user prompt when parsed through the modern journal format. The fix: extracts command from JSON-string and object-form tool arguments for bash-style tool calls, reuses the shared shell-command splitter, preserves the direct message.text prompt instead of the system/context-heavy rendered text, ignores malformed payloads without aborting the session parse.

What you expected

• Show used shell commands.

Output of codeburn --version

0.9.24

OS

Windows 11

Provider involved

Copilot

Steps to reproduce

Run codebrun command.

Redacted JSONL or SQLite snippet

No response

DEBUG=1 output

No response