WIP: Add `timerexistsname` and `utimerexistsname` Tcl commands to check timer existence

[ZarTek-Creole]

✅ Title

WIP: Add `timerexists` and `utimerexists` Tcl commands to check timer existence

📝 Description

## Summary

This pull request introduces two new experimental Tcl commands for Eggdrop:

- `timerexists <name>`
- `utimerexists <name>`

These commands allow script authors to check whether a timer or utimer with a given name currently exists.  
This is meant to complement `killtimer` and `killutimer` by providing a safe way to check existence before attempting to remove a timer.

---

## 🔧 Status

🚧 **Draft / WIP** — Not tested yet.  
Needs review and validation from Eggdrop core devs.

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## 📚 Proposed Commands

### `timerexists <timerName>`
Returns `1` if a timer with this name exists, `0` otherwise.

### `utimerexists <timerName>`
Same as above, but for secondly-based timers.

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## 💡 Motivation

Currently, scripts must use complex or error-prone workarounds to detect timers.  
This patch introduces a clean, reliable way to check if a timer/utimer exists by name.

### Example: current workaround

```tcl
set t [utimer 1 myTimer] 0 myTimer
if {[info exists t] && [catch {killutimer myTimer} error]} {
  putlog "Warning: Unable to kill utimer ($error)."
}

With this feature:

utimer 1 myTimer 0 myTimer
if {[utimerexists myTimer]} {
  killutimer myTimer
}

---

🧩 Integration details

• Implemented in src/tclmisc.c
• Reuses the logic from killtimer / killutimer
• No known side-effects
• Syntax is consistent with existing Eggdrop command naming (explicit and clear)

---

⚠️ Notes

• ❌ Not yet tested
• ❗ Documentation still needs to be updated (doc/tcl-commands.doc)
• 🧪 Needs review by maintainers to confirm viability, naming, behavior, etc.
• 🤝 Suggestions and improvements welcome

[michaelortmann]

i guess you want to add the documentation to doc/sphinx_source/using/tcl-commands.rst

[michaelortmann]

is there any relation to #507?

[crazycatdevs]

Good idea but with another name, as (u)timerexists is already existing in alltools.tcl and used by several scripts and doesn't search on the same argument (command vs name).