fix: channel attribution, dedup, cache bugs + channel edit/move (v1.19.0)

fix(packet_decoder): brute-force channel resolution when hash lookup fails

ChannelCrypto.calculate_channel_hash() and the MeshCore firmware compute
different channel identifiers for the same secret, causing _hash_to_idx to
return None for all hashtag-channel messages. Fallback: try each registered
key individually via a single-key keystore. First valid decryption wins.
Result cached in _hash_to_idx for O(1) resolution on subsequent packets.

fix(events): channel-agnostic sentinel prevents cross-channel duplicates

on_rx_log now marks '*' in DualDeduplicator after storing a message.
on_channel_msg checks this sentinel and suppresses storage regardless of
channel_idx or message_hash differences between the two library systems.
Fixes #mc-radar messages appearing in #weather and vice versa.

fix(events): secondary path-cache keyed by content for hash-mismatch

_path_cache keyed by meshcoredecoder hash; CHANNEL_MSG_RECV carries meshcore
hash (different value). Added _path_cache_by_content ("sender:text[:100]")
as fallback so path_hashes are recovered when the two hashes disagree.

fix(commands,cache): remove stale channel key after del_channel reindex

Cache entry for old_idx not removed after slot move, causing same channel
to appear twice. New DeviceCache.remove_channel_key(idx) called after each
move. asyncio.sleep(0.5) added before re-discovery to let device settle.

feat(channel_panel,commands,dashboard): channel edit — move/reindex support

First channel-edit capability in the GUI. New '↕️ Move / Reindex' mode in
Channel Manager dialog. Source channel selected from dropdown, target index
in number field. ↕ button inline with 🗑 in Messages and Archive submenus.
_cmd_move_channel reads secret from cache or device, writes new slot, clears
old slot, updates cache atomically, triggers re-discovery with settle delay.

meshcore_gui/services/cache.py

@@ -153,6 +153,20 @@ class DeviceCache:
         self._data["channel_keys"] = keys
         self.save()
 
+    def remove_channel_key(self, channel_idx: int) -> None:
+        """Remove a channel key from the cache and persist.
+
+        No-op if the index is not present.
+
+        Args:
+            channel_idx: Channel slot index whose key should be removed.
+        """
+        keys = self._data.get("channel_keys", {})
+        removed = keys.pop(str(channel_idx), None)
+        if removed is not None:
+            self._data["channel_keys"] = keys
+            self.save()
+
     # ------------------------------------------------------------------
     # Contacts (merge strategy)
     # ------------------------------------------------------------------