The binary make install builds retries a refused or unresolvable connection (closes #206)

Bun's `fetch`, which `~/bin/quak` runs under, rejects with a plain `Error`
that has no `cause` and a code of bun's own. Running the built binary against
local listeners gave `ConnectionRefused` for a refused connection and a failed
TLS handshake, and `ConnectionRefused` or `FailedToOpenSocket` for a name that
does not resolve. Both join `TRANSPORT_CODES` in `src/retry.ts`, so they are
retried and called transient. They stay out of `CONNECT_CODES`, so a `POST` or
`PUT` is not replayed on them, because bun also gives them when it resends a
request on a new connection. `classify` in `src/backup.ts` records a
`TimeoutError` as transient, so a stalled download is no longer `unknown`.

Not changed: a certificate bun rejects is not retried.

Model: opus-5-5

TODO.md

@@ -17,11 +17,10 @@ pre-1.0
 
 # Next Step
 
-Five bugs are open: https://git.eeqj.de/sneak/quak/issues/197,
+Four bugs are open: https://git.eeqj.de/sneak/quak/issues/197,
 https://git.eeqj.de/sneak/quak/issues/198,
-https://git.eeqj.de/sneak/quak/issues/199,
-https://git.eeqj.de/sneak/quak/issues/205 and
-https://git.eeqj.de/sneak/quak/issues/206. The check of quak against a live Ente
+https://git.eeqj.de/sneak/quak/issues/199 and
+https://git.eeqj.de/sneak/quak/issues/205. The check of quak against a live Ente
 account, https://git.eeqj.de/sneak/quak/issues/187, needs an account only sneak
 has, so it waits on him.
 
@@ -30,6 +29,19 @@ declares one.
 
 # Completed Steps
 
+- 2026-10-16: The `~/bin/quak` that `make install` builds retries a refused
+  connection and a name that does not resolve, and the backup records either as
+  transient (issue 206). Bun's `fetch` reports them with codes of its own,
+  `ConnectionRefused` and `FailedToOpenSocket`, which `src/retry.ts` now counts
+  as transport failures. A `POST` or `PUT` is not replayed on them, because bun
+  also gives them when it resends a request on a new connection after a
+  connection it kept open closed, and the server may already have the request.
+  Bun already gave `ECONNRESET` for a reset and a `TimeoutError` for a deadline.
+  `classify` in `src/backup.ts` now records any `TimeoutError` as transient, so
+  a stalled download, whose error says only that it stalled, is no longer
+  `unknown`. The shapes were found by running the binary against local
+  listeners.
+
 - 2026-10-15: A network failure is printed and recorded with its reason, not as
   just `fetch failed` (issue 196). `describeError` in `src/errors.ts` gives an
   error's message followed by the message of each error on its `cause` chain,