fix(connect): start retry backoff small instead of at ~1.4s

[mishushakov]

Problem

connect_forever (src/util.rs) is the retry loop behind every Socket::connect. When the peer's port isn't bound yet, transport::connect returns ConnectionRefused (correctly classified as retryable) and the loop sleeps before retrying.

The delay was computed as:

if try_num < 5 { try_num += 1 }                  // bumped to 1 BEFORE the first sleep
let delay = E.powf(try_num as f64 / 3.0)         // e^(1/3) ≈ 1.40
          + rng.random_range(0.0..0.1);          // + jitter

So the first retry already waits ~1.4s (then ~1.95s, ~2.7s, …). A peer whose kernel binds in ~330ms therefore isn't reached until ~1.4s — attempt #1 fails, the loop sleeps ~1.4s, attempt #2 succeeds.

Fix

Start the backoff small and grow it, mirroring the crate's existing ReconnectConfig semantics (exponential, capped, jittered):

const INITIAL: Duration = Duration::from_millis(50);
const MAX: Duration = Duration::from_secs(30);
let mut delay = INITIAL;
// ...
let jitter = rand::rng().random_range(0.0f64..0.1f64);
async_rt::task::sleep(delay + delay.mul_f64(jitter)).await;
delay = (delay * 2).min(MAX);

Retries now fall at ~50, 100, 200, 400ms… — a peer ready at ~330ms is reached at ~350ms instead of ~1.4s. Same semantics otherwise: still exponential, still capped at 30s, still jittered. The outer run_with_timeout(connect_timeout) (default 30s) still bounds a peer that never binds.

Testing

• cargo build succeeds
• cargo clippy --lib is clean

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