feat!: bridge on DongLoRa Protocol v2 and async client

The 1.0 bridge running on the async Dongle API from donglora-client 1.0.0 and the Protocol v2 wire format.

* Radio loop is now a tokio task, not a dedicated std::thread. Everything is async end to end.

* [radio] config schema: tx_power renamed to tx_power_dbm (plain i8, no "max" keyword), cad field removed (CAD is a per-TX flag in v1.0), default sync_word changed 0x3444 to 0x1424 to match the SX126x register encoding of MeshCore private sync byte.

* TX retry with backoff (new [tx] config section). Every TX runs through Dongle::tx_with_retry, retrying TX_DONE(CHANNEL_BUSY) and ERR(EBUSY) per PROTOCOL.md §6.10 / §C.5.5. Defaults: 3 attempts, 20-100 ms randomized backoff, doubling to 500 ms cap, 5 s per-attempt timeout. Configurable via max_attempts, backoff_min_ms, backoff_max_ms, backoff_cap_ms, backoff_multiplier, per_attempt_timeout_secs.

* TUI packet log shows retry state: in-flight retries render with a cycle marker in yellow and an N/M attempt counter, terminal TX failures render in red, post-retry success shows final attempt count.

* Stats gain tx_retries and tx_failures counters surfaced in StatsSnapshot.

* Measured airtime from TX_DONE replaces the theoretical estimate, feeding the rate limiter with the real on-air duration.

* The explicit 2 s liveness ping loop is gone. The Dongle runs a 500 ms internal keepalive, matching spec §3.4 inactivity window with 2x margin.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "donglora-bridge"
-version = "0.3.1"
+version = "1.0.0-alpha.1"
 edition = "2024"
 authors = ["Stephen Waits <steve@waits.net>"]
 license = "MIT"
@@ -14,7 +14,7 @@ rust-version = "1.94.1"
 exclude = [".jj/", ".github/"]
 
 [dependencies]
-donglora-client = "0.2"
+donglora-client = { path = "../client-rs", version = "1.0.0-alpha.1" }
 iroh = "0.97"
 iroh-gossip = "0.97"
 mainline = { version = "6", features = ["async"] }