feat(benchmarking): added bugs to QA benchmarking [FOU-80]

[mrchocha]

📋 Summary

This PR introduces a QA Benchmark Seed containing a set of intentional, toggleable bugs for use in QA benchmarking and performance evaluation. These bugs are safe, isolated, and can be enabled/disabled locally or via environment variables without impacting production.

---

🐛 Included Demo Bugs

Bug Name	Trigger Flag	Scope	Description
Shift+Enter Sends Message	localStorage.QA_BUG_SHIFT_ENTER_SEND = '1'	Client	Pressing Shift+Enter sends message instead of inserting newline
Muted Channel Still Notifies	QA_BUG_MUTED_CHANNEL_NOTIF=1	Server	Muted channel still triggers desktop notifications
Draft Lost on Room Switch	localStorage.QA_BUG_ERASE_DRAFT = '1'	Client	Draft disappears when switching rooms quickly
Paste Image Clears Text	localStorage.QA_BUG_PASTE_IMAGE_CLEARS_TEXT = '1'	Client	Pasting image clears existing composer text
Reaction Count Mismatch	localStorage.QA_BUG_REACTION_COUNT_MISMATCH = '1'	Client	Reaction count doesn’t update properly after removal
Thread Counter Not Decremented	localStorage.QA_BUG_THREAD_COUNTER_NOT_DECREMENTED = '1'	Client	Thread counter remains >0 after deleting last reply

---

🔧 Usage

Each bug is documented with:

• Enable/Disable instructions

• Reproduction steps

• Modified files

• Expected incorrect behavior

These can be found in qa-benchmark/ along with tickets.csv, which lists the bugs as realistic QA tickets.

---

🛡️ Safety

• Bugs are opt-in only (disabled by default)

• No side effects without explicitly enabling the respective flags

• No changes to production behavior unless deliberately toggled

---