Add decision-level structured logging for binding and rewrites

[sven1103-agent]

Summary

• Adds structured decision-level logs for session binding transitions and tool path rewrite decisions.
• Emits concise INFO events with deterministic skip reasons; DEBUG optionally includes before/after path details.
• Logs non-fatal plugin error stages that can affect runtime behavior.

Why

Issue #63 requests diagnosable runtime behavior without flooding logs, to support investigation of the remaining behavior issue in #62.

Verification

• npm test

Issues

• Closes Add decision-level logging for worktree binding and path rewrite behavior #63
• Supports Plugin loads, but write flow is not redirected into prepared worktree #62