fix: padlocks unclickable, From-radio level inert, callsign field too narrow

Padlocks. LockBtn was declared INSIDE the App component, so every render gave
React a new component type and the button was unmounted and rebuilt — about four
times a second while the CAT polls. It flickered under the pointer and swallowed
clicks, because the node being clicked no longer existed when the click landed.
The padlock now lives at module level and is passed its state.

From-radio level. It reached the QSO recorder and nothing else, so an operator
listening through OpsLog heard no difference between 10% and 150% — the control
was not weak, it was disconnected. It now scales the monitor too, applied on the
captured chunk so the network-fed path keeps its own levels, and a running
monitor picks up a change immediately: making someone restart the monitor to
hear the slider is how a working control gets reported as broken.

Callsign field widened to w-56, the room coming from the RST pair which never
needs more than five characters. It is the one field always typed into, it
carries the REC badges, and a long portable call has to stay readable.

changelog.json

@@ -6,13 +6,19 @@
       "Cluster filters gain NEW POTA and NEW COUNTY, alongside the existing status chips.",
       "A playback that fails to start now says so in the log instead of ending silently after a tenth of a second.",
       "Replaying a recording before the previous one has finished now works: the new playback waits for the audio device to be free instead of keying the radio and releasing at once.",
-      "The play button becomes a stop button while the recording is going out: it cuts the transmission and releases the PTT, and you can send it again straight away."
+      "The play button becomes a stop button while the recording is going out: it cuts the transmission and releases the PTT, and you can send it again straight away.",
+      "The \"From radio\" level now applies to what you HEAR through OpsLog, not only to recordings, and takes effect while the monitor is running.",
+      "The padlocks on frequency, band, mode and times no longer flicker under the pointer and refuse the click.",
+      "The callsign field is wider, taking the room from the RST pair."
     ],
     "fr": [
       "Les filtres du cluster gagnent NEW POTA et NEW COUNTY, à côté des pastilles de statut existantes.",
       "Une lecture qui ne démarre pas le signale désormais dans le journal, au lieu de s'arrêter en silence au bout d'un dixième de seconde.",
       "Relancer un enregistrement avant la fin du précédent fonctionne désormais : la nouvelle lecture attend que le périphérique audio soit libre, au lieu de passer en émission et de relâcher aussitôt.",
-      "Le bouton de lecture devient un bouton d'arrêt pendant l'émission de l'enregistrement : il coupe l'émission et relâche le PTT, et vous pouvez le renvoyer aussitôt."
+      "Le bouton de lecture devient un bouton d'arrêt pendant l'émission de l'enregistrement : il coupe l'émission et relâche le PTT, et vous pouvez le renvoyer aussitôt.",
+      "Le niveau « From radio » agit désormais sur ce que vous ENTENDEZ dans OpsLog, et plus seulement sur les enregistrements ; il prend effet moniteur en marche.",
+      "Les cadenas de fréquence, bande, mode et heures ne scintillent plus sous le curseur et acceptent le clic.",
+      "Le champ indicatif est plus large, la place venant de la paire RST."
     ]
   },
   {