Initial implementation of demon CLI tool

Implement complete daemon process management CLI with the following features:
- demon run: spawn background processes with stdout/stderr redirection
- demon stop: graceful process termination with SIGTERM/SIGKILL timeout
- demon tail: real-time file watching and log tailing
- demon cat: display log file contents
- demon list: show all managed processes with status
- demon status: detailed process information
- demon clean: remove orphaned files from dead processes

Technical implementation:
- Uses clap for CLI with enum-based subcommands
- Structured logging with tracing crate
- File watching with notify crate for efficient tailing
- Process management with proper signal handling
- Creates .pid, .stdout, .stderr files in working directory
- Comprehensive error handling and edge case coverage

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

Co-Authored-By: Claude <[email protected]>

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+# project goals
+the goal of this project is to create a cli tool named `demon` that should be used to spawn background processes and redirect their stdout and stderr to files.
+here is an overview of the subcommands the tool should provide and their usage:
+
+## demon run
+```
+# the identifier is a required argument
+# all remaining arguments will be used to spawn the process with the first one being the executable name
+# three files should be created `.pid`, `.stdout`, `.stderr`
+# the cli tool should exit immediatly but the spawned process should be left running the background
+demon run --id <identifier> <command...>
+
+# example usage
+demon run --id npm-dev npm run dev
+# this should create the files `npm-dev.pid`, `npm-dev.stdout` and `npm-dev.stderr`
+# if the pid file already exists and the process is still running you should fail with a descriptive error message
+```
+
+## demon stop
+```
+# this should kill the process if it is running, otherwise do nothing
+demon stop --id <id>
+```
+
+## demon tail
+```
+# this should tail both .stderr and .stdout files by default, or just the selected ones
+demon tail [--stdout] [--stderr] --id <id>
+```
+
+## demon cat
+```
+# this should cat both files or just the selected ones
+demon cat [--stdout] [--stderr] --id <id>
+```