feat: average rating stat

[LeonTheDev-io]

Adds average ticket rating statistic

This PR introduces a new feature that calculates and displays the average rating for closed tickets. The average rating is available in relevant API responses and placeholders (Opening Message, Bot Activity) ({avgRating}).

Versioning information

• This includes major changes (breaking changes)
• This includes minor changes (minimal usage changes, minor new features)
• This includes patches (bug fixes)
• This does not change functionality at all (code refactoring, comments)

Is this related to an issue?

None found

Changes made

• Added support for calculating and displaying the average ticket rating (avgRating) across the bot:
  • Implemented getAverageRating in the stats worker and exposed it via the stats pool.
  • Updated ticket manager, client ready listener, and API routes to fetch and include average rating in stats.
  • Updated stat placeholders in messages and activity strings to support {avgRating}.
  • Ensured average rating is formatted to one decimal place where displayed.

Confirmations

• I have updated related documentation (if necessary) docs: add documentation for avgRating placeholder docs#51
• My changes use consistent code style
• My changes have been tested and confirmed to work

[RooRay]

looks good! i'll test this on my own instance now and check all is good.

in the meantime, the docs need to be updated with the new placeholders and other details. do you think you could do this?

[LeonTheDev-io]

PR for the docs is linked above
Tell me if I missed something

[RooRay]

PR for the docs is linked above Tell me if I missed something

whoops sorry I just realised that 😂

[RooRay]

changes look good! testing confirms no issues

[RooRay]

there we go, after I totally didn't nuke my test bots .env file I managed to test everything and all looks great! thank you for your contributions!