fix: resolve powershell parse errors and session file corruption

CRITICAL FIXES:

1. PowerShell Parse Error (lines 1598, 1620):
   - Changed $toolName: to ${toolName}: to avoid drive syntax interpretation
   - Prevents "Variable reference is not valid" errors
   - Script can now execute without syntax errors

2. Write-SessionFile Corruption Fix:
   - Initialize $fileStream = $null and $writer = $null at loop start
   - Add $writer.Dispose() in finally block
   - Increase ConvertTo-Json depth from default to 100
   - Proper disposal order prevents 0-byte session files

3. Enhanced Debugging:
   - Added extensive Write-Host checkpoints in Handle-OptimizeToolOutput
   - Added script version logging
   - Added DIAGNOSTIC logs for optimize-tool-output action

Root Cause Analysis (via Gemini CLI):
- Each orchestrator invocation runs in NEW PowerShell process
- No shared in-memory state between invocations
- current-session.txt is ONLY mechanism for state sharing
- Parse error prevented script execution entirely
- Improper file disposal caused 0-byte session files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ooples