Bump HTTP procedure timeouts (500ms/10s → 30s/180s) and fix docs (#4630)

Relates to #4608

## Timeout bump

The previous defaults for HTTP requests in procedures were far too
restrictive:

| | Before | After |
|---|---|---|
| Default (no timeout set) | 500ms | **30s** |
| Maximum (clamp ceiling) | 10s | **180s** |

Users are hitting the 10s ceiling when calling LLM APIs (OpenAI, Gemini,
etc.) from procedures. These APIs routinely take 30-120 seconds,
especially for image/vision models. The 500ms default also caused silent
failures for users who did not explicitly set a timeout.

### Comparable platforms
- **Supabase Edge Functions**: 150s (free) / 400s (pro) total execution
- **Vercel Functions**: 10s (hobby) / 60s (pro) / 300s (enterprise)
total
- **Convex actions**: 120s limit
- **AWS Lambda**: up to 15 min total
- **Firebase/GCF**: 60s default, configurable up to 540s

Most platforms do not separately clamp outbound HTTP timeouts at all.

## Docs fix

The procedures docs page had a note inside the C++ tab only that said
`All timeouts are clamped to a maximum of 500ms by the host`. This was
wrong (the max was 10s, not 500ms) and buried in the wrong place
(applies to all languages, not just C++).

Moved the note outside the language tabs and updated the values to match
the new code.

### Changes
- `crates/core/src/host/instance_env.rs`: `HTTP_DEFAULT_TIMEOUT` 500ms →
30s, `HTTP_MAX_TIMEOUT` 10s → 180s
- `docs/.../procedures.md`: Fix and relocate timeout note

---------

Co-authored-by: clockwork-labs-bot <clockwork-labs-bot@users.noreply.github.com>

Author: clockwork-labs-bot

crates/core/src/host/instance_env.rs

@@ -970,12 +970,16 @@ impl InstanceEnv {
 
 /// Default timeout for HTTP requests performed by [`InstanceEnv::http_request`].
 ///
-/// Value chosen arbitrarily by pgoldman 2025-11-18, based on little more than a vague guess.
-const HTTP_DEFAULT_TIMEOUT: Duration = Duration::from_millis(500);
+/// Applied when the module does not specify a timeout.
+/// 30 seconds is generous enough for most external API calls (including LLM APIs)
+/// without silently hanging forever on a broken endpoint.
+const HTTP_DEFAULT_TIMEOUT: Duration = Duration::from_secs(30);
 /// Maximum timeout for HTTP requests performed by [`InstanceEnv::http_request`].
 ///
 /// If the user requests a timeout longer than this, we will clamp to this value.
-const HTTP_MAX_TIMEOUT: Duration = Duration::from_secs(10);
+/// 180 seconds accommodates long-running LLM and AI API calls,
+/// which routinely take 30-120 seconds for complex requests.
+const HTTP_MAX_TIMEOUT: Duration = Duration::from_secs(180);
 const BLOCKED_HTTP_ADDRESS_ERROR: &str = "refusing to connect to private or special-purpose addresses";
 
 struct FilteredDnsResolver;

docs/docs/00200-core-concepts/00200-functions/00400-procedures.md

@@ -873,15 +873,15 @@ SPACETIMEDB_PROCEDURE(Unit, get_request_with_short_timeout, ProcedureContext ctx
 }
 ```
 
-:::note
-All timeouts are clamped to a maximum of 500ms by the host.
-:::
-
 Procedures can't send requests at the same time as holding open a [transaction](#accessing-the-database).
 
 </TabItem>
 </Tabs>
 
+:::note
+If no timeout is specified, HTTP requests default to 30 seconds. User-specified timeouts are clamped to a maximum of 180 seconds by the host.
+:::
+
 ## Calling Reducers from Procedures
 
 Procedures can call reducers by invoking them within a transaction block. The reducer function runs within the transaction context: