Adding CLI client for MacOS

[jfwoods]

System now supports daemon interaction via CLI!!! No hardware required anymore.

[Copilot]

Pull request overview

This PR adds a new local CLI (linkctl) to control an Insta360 Link camera by talking to linkctl-daemon over a new TCP control socket, enabling camera control without requiring the existing WebSocket client/hardware UI flow.

Changes:

• Introduces host/linkctl CLI client (POSIX C) with one-shot commands and an interactive jog mode.
• Adds a TCP control socket to linkctl-daemon (port 9001) and a background service loop to process CLI commands.
• Updates WebSocket command handling to emit an "ack" response for non-status commands; updates .gitignore for CMake build dirs.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
host/linkctl/README.md	Documents building/using the new linkctl CLI and jog mode.
host/linkctl/linkctl.c	Implements TCP client commands + interactive jog mode.
host/linkctl/CMakeLists.txt	Adds CMake build/install for linkctl.
host/linkctl-daemon/control.h	Declares the new TCP control socket interface and default port.
host/linkctl-daemon/control.c	Implements line-based TCP control protocol and camera command dispatch.
host/linkctl-daemon/main.c	Starts the TCP control service loop in a new pthread; integrates init/shutdown.
host/linkctl-daemon/server.c	Adds WebSocket "ack" messages for successful non-status commands.
host/linkctl-daemon/CMakeLists.txt	Adds control.c to daemon build.
.gitignore	Ignores host/*/build/ directories.

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