fix: eliminate production panics and unwraps in orchestration layer

[laynepenney]

Summary

Phase 1 of Production Readiness Plan: Eliminate all production panics, unwraps, and expects in the orchestration layer.

Changes

New Error Types

• Created comprehensive IpcError enum with 17 error variants
• Added from_io_error() helper for IO error conversion
• Exported via src/orchestrate/ipc/mod.rs

Fixed Production Issues

• client.rs:347 - Message request_id handling with proper error propagation
• commander.rs:197 - Socket path using as_os_str() for safe path handling
• worktree.rs - 3 unwraps fixed (worktree add/remove paths)
• griptree.rs - 4 unwraps fixed (worktree operations)
• terminal_ui.rs - Removed unused Stylize import

Safety Improvements

• All path conversions now use to_string_lossy() or as_os_str()
• No more unwrap() or expect() in production orchestration code
• Proper error propagation with context

Verification

• All production unwraps in orchestration layer fixed
• Path handling safe for all valid paths
• Clean build with reduced warnings
• Comprehensive error types implemented

Related

• Implements Phase 1 of docs/PRODUCTION_READINESS_PLAN.md
• Addresses production readiness assessment findings