feat(chat): make streaming and chat timeouts per-profile configurable

The chat request previously used a hard-coded 30 s timeout and ignored
--read-timeout entirely (that flag only bounded URL prompt fetching), so
slow reasoning models were cut off mid-generation unless one remembered
to pass --stream (which used a separate hard-coded 600 s).

Resolve `stream`, `read_timeout` and `connect_timeout` from
[default]/[model.<profile>] into PromptConfig and wire the (connect, read)
timeout into both the streaming and non-streaming chat calls. CLI
--stream/--read-timeout/--connect-timeout still override; the two timeout
flags default to None so a config value can win, with the URL-fetch
fallbacks (3 s/10 s) preserved. Default chat read_timeout is now 600 s.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Per-profile chat streaming and chat-request timeouts: `stream`, `read_timeout`
+  and `connect_timeout` are now resolvable in `[default]`/`[model.<profile>]`
+  (CLI `--stream`/`--read-timeout`/`--connect-timeout` still override).
+
+### Changed
+- The chat request now honors the configured `(connect, read)` timeout instead
+  of a hard-coded 30 s; the default `read_timeout` is 600 s so slow reasoning
+  models are no longer cut off mid-generation.
+
 ## [0.1.0] - 2026-07-07
 
 Initial release. Replaces the previous collection of shell scripts