fix: Slug hook useEffect error affecting title input

[apburnes]

Closes #211

Changes proposed in this pull request:

• Remove the useEffect from the slug field to avoid uncontrolled update loop
• Change the default slug lock value to false
• The slug field will always URL escape the related slug field (defaults to title) unless locked

Security considerations

None

[kevinsmaster5]

Looks good. Tested locally, no more title editing character ghost deletion.