Add QR pairing (terminal QR, in-app scanner, iris://pair deep link)

gateway-plugin/channels.py

@@ -3,9 +3,9 @@
 Maps app concepts onto hermes' existing ``chat_id`` / ``thread_id`` primitives
 (docs/06-channels-cron-search.md §6.1):
 
-* **default chat**  -> the home channel (``ANDROID_HOME_CHANNEL``, default
-  ``android:default``), ``kind="default"``, ``is_default=1``.
-* **user channel**  -> a minted ``chat_id = android:chan_<n>``, ``kind="channel"``.
+* **default chat**  -> the home channel (``IRIS_HOME_CHANNEL``, default
+  ``default``), ``kind="default"``, ``is_default=1``.
+* **user channel**  -> a minted ``chat_id = chan_<n>``, ``kind="channel"``.
 * **thread**        -> a minted ``thread_id = t_<n>`` under a ``chat_id``,
   ``kind="thread"`` (stored with its ``parent_chat_id``).
 
@@ -15,7 +15,7 @@ directory (``gateway/channel_directory.py``) via the adapter's
 ``list_channels()`` hook, so ``send_message`` / cron can resolve a friendly
 name (e.g. "Cron Reports") to a chat_id.
 
-Storage: ``get_hermes_home()/"android"/channels.db``.
+Storage: ``get_hermes_home()/"iris"/channels.db``.
 
 Milestone M3.
 """
@@ -37,12 +37,12 @@ KIND_CHANNEL = "channel"
 KIND_THREAD = "thread"
 
 # chat_id / thread_id minting prefixes.
-CHANNEL_PREFIX = "android:chan_"
+CHANNEL_PREFIX = "chan_"
 THREAD_PREFIX = "t_"
 
 
 class ChannelDirectory:
-    """Persistent channel directory under ``get_hermes_home()/"android"``.
+    """Persistent channel directory under ``get_hermes_home()/"iris"``.
 
     Thread-safe (single connection + lock); all operations are small and fast
     enough to run inline on the gateway's asyncio loop. Mirrors the
@@ -127,7 +127,7 @@ class ChannelDirectory:
         when it was still the auto default); if another row is marked default
         it is cleared so exactly one default exists.
         """
-        chat_id = (chat_id or "android:default").strip() or "android:default"
+        chat_id = (chat_id or "default").strip() or "default"
         name = (name or "Default").strip() or "Default"
         with self._lock:
             existing = self._conn.execute(
@@ -443,6 +443,6 @@ def get_directory() -> ChannelDirectory:
                 # failure is not actionable.
                 with contextlib.suppress(Exception):
                     _directory.close()
-            _directory = ChannelDirectory(home / "android" / "channels.db")
+            _directory = ChannelDirectory(home / "iris" / "channels.db")
             _directory_home = home
         return _directory