Model selection command arguments, reasoning effort autocompletion, transient retry handling, and UI…

Adds direct /model switching with inline ghost text autocompletion, dynamic /effort hint completion, artifact filesystem event coalescing, and fixes for transient HTTP 502 retries, CPU redraw utilization, and Windows path resolution.

• Added a /model argument to switch models by name, slug, or label and set defaults in one step with inline ghost text autocompletion.
• Improved the /effort hint to complete typed text dynamically instead of displaying a static placeholder.
• Improved artifact handling in sessions generating many files by coalescing bursts of filesystem events into a single rescan.
• Fixed selectable reasoning effort configuration for Gemini 3.1 Pro and Gemini 3.5 Flash when authenticating via Gemini API keys.
• Fixed continuous interface redraws when the tasks panel or subagent detail panel was open with no active tasks, significantly reducing idle CPU usage.
• Fixed running subagent elapsed timers freezing on screen while the parent agent was in a waiting state.
• Fixed transient HTTP 502 Bad Gateway errors terminating runs by adding automatic retry handling with backoff.
• Fixed self subagents launched from unconfigured sessions re-resolving configurations from scratch and drifting from parent autonomous execution modes.
• Fixed Windows file deletion sharing violations by retrying deletions with backoff before failing.
• Fixed headless daemon startup banner printing unsupported localhost browser URLs to service manager logs.
• Fixed the built-in migrate-workflows skill to properly handle Windows path separators and home directories.