Add LoRa support with background sync and settings UI

- Progressive retry in rns_client.py: fast timeout (15s) then slow (60s+)
  for LoRa/multi-hop links, with automatic fallback
- Background sync threads so subscriptions page returns immediately
  with syncing/error status indicators per subscription
- LoRa RNode configuration in settings page with serial port and
  expandable advanced radio settings (frequency, bandwidth, etc.)
- Internet transport now toggleable alongside LoRa — users can
  enable one, the other, or both
- Reticulum config auto-generated from settings on startup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

rns_client.py

@@ -1,9 +1,15 @@
+import json
 import time
 import RNS
 
 APP_NAME = "tinyweb"
 ASPECTS = ["server"]
-REQUEST_TIMEOUT = 30
+
+# Two-tier timeout profiles: fast first, then slow for LoRa/multi-hop links
+_TIMEOUT_TIERS = [
+    {"path": 15, "link": 15, "request": 30, "poll": 0.25},
+    {"path": 60, "link": 60, "request": 120, "poll": 1.0},
+]
 
 
 def fetch_remote_sites(dest_hash_hex, since=""):
@@ -11,18 +17,40 @@ def fetch_remote_sites(dest_hash_hex, since=""):
     Connect to a remote TinyWeb instance over Reticulum and fetch its
     shared sites. Returns the response dict from /api/sites, or raises
     an exception on failure. Pass `since` as ISO timestamp for delta sync.
+
+    Uses progressive timeouts: tries fast first, then retries with longer
+    timeouts for slow links (LoRa, multi-hop).
     """
+    last_error = None
+    for tier in _TIMEOUT_TIERS:
+        try:
+            return _fetch(dest_hash_hex, since, tier)
+        except PermissionError:
+            raise  # Don't retry permission errors
+        except Exception as e:
+            last_error = e
+            continue
+    raise ConnectionError(
+        f"Could not reach {dest_hash_hex} after {len(_TIMEOUT_TIERS)} attempts: {last_error}"
+    )
+
+
+def _fetch(dest_hash_hex, since, timeouts):
+    """Single fetch attempt with the given timeout profile."""
     dest_hash = bytes.fromhex(dest_hash_hex)
+    poll = timeouts["poll"]
 
     # Resolve path if needed
     if not RNS.Transport.has_path(dest_hash):
         RNS.Transport.request_path(dest_hash)
         elapsed = 0
-        while not RNS.Transport.has_path(dest_hash) and elapsed < 15:
-            time.sleep(0.5)
-            elapsed += 0.5
+        while not RNS.Transport.has_path(dest_hash) and elapsed < timeouts["path"]:
+            time.sleep(poll)
+            elapsed += poll
         if not RNS.Transport.has_path(dest_hash):
-            raise ConnectionError(f"Could not find path to {dest_hash_hex}")
+            raise ConnectionError(
+                f"Could not find path to {dest_hash_hex} ({timeouts['path']}s timeout)"
+            )
 
     server_identity = RNS.Identity.recall(dest_hash)
     if server_identity is None:
@@ -39,15 +67,16 @@ def fetch_remote_sites(dest_hash_hex, since=""):
     # Establish link
     link = RNS.Link(destination)
     elapsed = 0
-    while link.status == RNS.Link.PENDING and elapsed < 15:
-        time.sleep(0.25)
-        elapsed += 0.25
+    while link.status == RNS.Link.PENDING and elapsed < timeouts["link"]:
+        time.sleep(poll)
+        elapsed += poll
 
     if link.status != RNS.Link.ACTIVE:
-        raise ConnectionError(f"Could not establish link to {dest_hash_hex}")
+        raise ConnectionError(
+            f"Could not establish link to {dest_hash_hex} ({timeouts['link']}s timeout)"
+        )
 
     try:
-        # Request /api/sites
         query = {"since": [since]} if since else {}
         request_data = {
             "method": "GET",
@@ -57,13 +86,14 @@ def fetch_remote_sites(dest_hash_hex, since=""):
             "gateway_host": "",
         }
 
-        receipt = link.request("/tinyweb", data=request_data, timeout=REQUEST_TIMEOUT)
+        req_timeout = timeouts["request"]
+        receipt = link.request("/tinyweb", data=request_data, timeout=req_timeout)
 
         elapsed = 0
         done = (RNS.RequestReceipt.READY, RNS.RequestReceipt.DELIVERED, RNS.RequestReceipt.FAILED)
-        while receipt.get_status() not in done and elapsed < REQUEST_TIMEOUT:
-            time.sleep(0.5)
-            elapsed += 0.5
+        while receipt.get_status() not in done and elapsed < req_timeout:
+            time.sleep(poll)
+            elapsed += poll
 
         if receipt.get_status() in (RNS.RequestReceipt.READY, RNS.RequestReceipt.DELIVERED):
             resp = receipt.get_response()
@@ -71,9 +101,10 @@ def fetch_remote_sites(dest_hash_hex, since=""):
                 raise PermissionError("That instance has sharing disabled.")
             if resp["status"] != 200:
                 raise ConnectionError(f"Remote returned status {resp['status']}")
-            import json
             return json.loads(resp["body"])
         else:
-            raise ConnectionError(f"Request failed or timed out")
+            raise ConnectionError(
+                f"Request failed or timed out ({req_timeout}s timeout)"
+            )
     finally:
         link.teardown()