feat(telemetry): add PostHog telemetry for CLI usage analytics

[gtrrz-victor]

Summary

Add anonymous usage telemetry using PostHog to understand CLI usage patterns:

• Track command name and success/failure status per execution
• Uses hashed machine ID as distinct identifier (via machineid library)
• Opt-out via ENTIRE_TELEMETRY_OPTOUT=1 environment variable
• Skips hidden commands, help, and completion from tracking
• Fails gracefully - telemetry errors never affect CLI functionality

What's Collected

Property	Example
command	"entire rewind", "entire status"
flags	"no-telemetry,strategy,help"
success	true/false
cli_version	"1.0.0"
os	"darwin", "linux"
arch	"arm64", "amd64"
in_ci	true/false

Consent Flow:

• Interactive mode: Shows a confirmation prompt ("Help improve Entire CLI?") with "Yes" as default
• Non-interactive mode: Defaults to enabled, use --no-telemetry flag to disable
• Respects ENTIRE_TELEMETRY_OPTOUT env var (always takes priority)
• Prompt only shown once; preference stored in .entire/settings.json

Settings:

• Added telemetry field to settings (*bool: nil = not asked, true = enabled, false = disabled)
• --no-telemetry flag always overrides existing setting

[Soph]

I would suggest we add this also to entire enable. We would like to gather some metrics, are you ok with that? something like that. I would be open about it and let people opt out. A bit like the Apple does.

[gtrrz-victor]

I would suggest we add this also to entire enable. We would like to gather some metrics, are you ok with that? something like that. I would be open about it and let people opt out. A bit like the Apple does.

What about this?