feat: add !uptime prefix command + improve DISCORD_TOKEN error message

[Ghraven]

Closes #9
Closes #7

What

1. !uptime command (prefixcommands/uptime.py)

• Records bot start time when the cog loads using datetime.now(timezone.utc)
• Calculates elapsed days, hours, minutes, seconds
• Outputs human-readable string e.g. Bot Uptime: 2 days, 14 hours, 35 minutes
• Omits zero-value leading units (shows seconds only if uptime < 1 minute)
• Follows exact same pattern as prefixcommands/ping.py (Cog class + type hints)
• Works in both guilds and DMs

2. Better DISCORD_TOKEN error (bot.py)

• Replaces the generic one-liner RuntimeError with a clear 3-step message
• Tells users exactly what to do: copy .env.example, fill in token, link to Discord dev portal
• Also registers prefixcommands.uptime in the extensions list

Example output

!uptime
Bot Uptime: 1 day, 3 hours, 22 minutes

Files changed

• prefixcommands/uptime.py — new file
• bot.py — register uptime extension + improve token error message

[TrivCodez]

PR Review

Status: ✅ Code Approved, ⚠️ Scope Note, ⏳ Awaiting Star

✅ Quality

• Excellent type hints & patterns
• Clean uptime formatting
• Clear error messages
• Follows existing style

⚠️ Scope Note

PR addresses multiple issues (#9 + #7). Future: one issue per PR for cleaner history.

⛔ Requirements Check

Missing: Repository Star

@Ghraven — You must ⭐ star this repository before merge.

Action: Click ⭐ at https://github.com/IN3PIRE/pn then comment here.

📝 Next Steps

Once starred → merge. Code is production-ready despite scope.

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Review includes star verification requirement

[Ghraven]

Thanks for the thorough review, @TrivCodez! Really appreciate the kind words on the code quality.

I've gone ahead and starred the repository ⭐ — happy to support the project!

Noted on the scope point too — going forward I'll keep PRs focused on a single issue. Good habit to build.