Add scaling and other enhancements to Streamlit UI for post-processing

[pineapple-cat]

Addresses:

• [x] #301
• [x] #268
• [x] Help text popups for some fields.
• [x] Streamlit warnings for invalid actions.
• [x] Debug extra columns.
• [x] Debug custom filter values.

[ilectra]

I'm not sure I understand all the bugfixes, but it works beautifully!