Filter edit screen shows "Discard changes?" without any edit

[salmon-21]

Description

Opening a filter for editing and going back without changing anything wrongly shows the "Discard changes?" confirmation dialog (added in #245).

Steps to reproduce

1. Open an existing filter (or one with prefilled fields) in the filter edit screen.
2. Background the app and return (onPause → onResume) — touch nothing.
3. Press back.
4. → "Discard changes?" appears, even though nothing was edited.

Cause

EditFilterFragment.render() pushes state into the fields via setTextIfDifferent(...) → EditText.setText(...). That setText fires the field's doAfterTextChanged watcher, which sends an Update… command, and the reducer flips isDirty = true. So a pure render is mistaken for a user edit.

The watcher is attached on onResume / detached on onPause (core/ui/base/.../TextViewExt.kt), so the spurious dirty reliably triggers after any onPause→onResume cycle where a render runs with the watcher attached.

Present on master since #245 (the same setTextIfDifferent + watcher pattern exists at a9baf26).

Fix

PR #247 makes the programmatic setText path watcher-safe: doAfterTextChanged returns a setter that suppresses the watcher while applying a render, and render() uses it instead of setText(). The isDirty-in-reducer design and TEA back-routing from #245 are unchanged. Verified on-device (SM-S948Q / Android 16): no spurious dirty after an onPause/onResume cycle, and a real edit still triggers the dialog.