File-association list view in settings + fix ghost glyphs after window moves

- New 'Filformat' row in the settings dialog opens a list of all
  [open_with] associations (.ext → command) plus the default editor;
  Delete removes an association (persisted to config.toml), Esc goes
  back
- Ghost fix: some terminals leave the right half of wide glyphs
  (emoji) behind when the diff only rewrites part of them — windows
  being dragged/resized/closed/snapped now request one full terminal
  repaint on completion, clearing any leftovers. Verified the
  compositor itself is clean (headless frames have no ghosts)
- Integration suite: 41/41

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/integration.py

@@ -440,6 +440,27 @@ def main():
         app.send({"type": "close_window", "window_id": op2["id"]})
         time.sleep(0.3)
 
+        # ── 4j. Associationsvyn i inställningarna ────────────────────────
+        disp.send(mouse_event({"Down": "Left"}, gx, 0))
+        disp.send(mouse_event({"Up": "Left"}, gx, 0))
+        text = disp.frame_text(timeout=5.0, contains="Filformat")
+        check("inställningarna visar filformat-raden", "1 associationer" in text,
+              f"frame: {text[:300]!r}")
+        for _ in range(5):
+            disp.send(key_event(code="Down"))
+        disp.send(key_event(code="Enter"))
+        text = disp.frame_text(timeout=5.0, contains=".txt")
+        check("associationsvyn listar .txt → less",
+              ".txt" in text and "less" in text)
+        disp.send(key_event(code="Delete"))
+        time.sleep(0.5)
+        cfg_now = open(os.path.join(cfgdir, "config.toml")).read()
+        check("Delete tar bort associationen ur config",
+              'txt = "less"' not in cfg_now)
+        disp.send(key_event(code="Esc"))
+        disp.send(key_event(code="Esc"))
+        time.sleep(0.3)
+
         # ── 5. Popup + popup_result via Enter ───────────────────────────
         app.send({
             "type": "spawn_popup", "message": "Integrationstest?",