feat(driver): add HTTP routes, startup split, and binary envelope support

Wire controller messages through new modules (background tasks, runtime state,
startup) and add binary envelope handling.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/background_tasks.py

@@ -0,0 +1,42 @@
+import asyncio
+import gc
+import utime
+
+from hello import broadcast_hello_udp
+
+
+async def presets_loop(presets, wdt):
+    last_mem_log = utime.ticks_ms()
+    while True:
+        presets.tick()
+        wdt.feed()
+        if bool(getattr(presets, "debug", False)):
+            now = utime.ticks_ms()
+            if utime.ticks_diff(now, last_mem_log) >= 5000:
+                gc.collect()
+                print("mem runtime:", {"free": gc.mem_free(), "alloc": gc.mem_alloc()})
+                last_mem_log = now
+        # tick() does not await; yield so UDP hello and HTTP/WebSocket can run.
+        await asyncio.sleep(0)
+
+
+async def udp_hello_loop_after_http_ready(sta_if, settings, wdt, runtime_state):
+    """Broadcast hello at startup-fast cadence, then slower cadence."""
+    await asyncio.sleep(1)
+    started_ms = utime.ticks_ms()
+    while True:
+        if runtime_state.hello:
+            print("UDP hello: broadcasting...")
+            try:
+                broadcast_hello_udp(
+                    sta_if,
+                    settings.get("name", ""),
+                    wait_reply=False,
+                    wdt=wdt,
+                    dual_destinations=True,
+                )
+            except Exception as ex:
+                print("UDP hello broadcast failed:", ex)
+        elapsed_ms = utime.ticks_diff(utime.ticks_ms(), started_ms)
+        interval_s = 5 if elapsed_ms < 60000 else 60
+        await asyncio.sleep(interval_s)