fix(bb-docs): give the recursive example test a 4-CPU budget to stop CI timeouts (#24268)

## What

The `barretenberg/docs` recursive example test (`recursive.test.ts ›
should generate recursive proof`) intermittently times out in CI and
fails the docs test job. This gives it more CPU so it stops tripping the
jest timeout.

## Why

The test proves a recursive circuit — a full in-circuit UltraHonk
verifier — in WASM via the pinned `@aztec/bb.js@0.87.9`. ci3 budgets
each test only `CPUS=2` by default, so the prover (started with
`threads: 8`) gets ~2 cores under contention and the prove + verify
lands in a ~140–341s band that straddles the 300s per-test cap.

It is **flaky, not a regression**: the same test passes and fails on
unrelated PRs purely with machine load (e.g. 295s ✅, 297s ✅, 318s ❌ on
one non-barretenberg PR). Measured locally, `CPUS=4` roughly halves the
proof time (~1.6×), bringing the worst observed run (341s) down to ~215s
— comfortably under cap.

## Changes

- `barretenberg/docs/bootstrap.sh` — budget the docs test `CPUS=4` (was
the default 2). ci3's outer `TIMEOUT` stays at its 600s default.
- `barretenberg/docs/examples/recursive.test.ts` — nudge the jest
per-test cap 300s → 360s as a guardrail.

No change to the example, circuits, or proof — only CI scheduling and
one timeout. Editing `bootstrap.sh` busts the docs build hash, so this
PR's CI re-runs `barretenberg/docs/bootstrap.sh test` under the new
budget (= the green check).

Author: iakovenkos

barretenberg/docs/bootstrap.sh

@@ -32,7 +32,10 @@ function build {
 }
 
 function test_cmds {
-  echo "$hash barretenberg/docs/bootstrap.sh test"
+  # The recursive example proves a circuit embedding a full in-circuit Honk verifier in WASM; on the
+  # default 2-CPU budget that prove+verify lands ~140-340s and intermittently trips the jest timeout.
+  # A 4-CPU budget roughly halves it, back well under the per-test cap.
+  echo "$hash:CPUS=4 barretenberg/docs/bootstrap.sh test"
 }
 
 function test {

barretenberg/docs/examples/recursive.test.ts

@@ -134,5 +134,5 @@ describe('Recursive Aggregation Example', () => {
     // Verify the recursive proof
     const isValid = await recursiveBackend.verifyProof(recursiveProofData);
     expect(isValid).toBe(true);
-  }, 300000);
+  }, 360000);
 });