hive-agent: cap the whole plugin install sequence, not just each call

The calls run serially before the web UI is served, so a per-call deadline
alone left N x 2 min of boot delay (8 min with the default two
marketplaces and two plugins, 10 with auto-update) when the fetch path is
blackholed. One shared 4 minute budget now bounds the sequence: each call
gets min(2 min, what is left), and calls after the budget is spent fail at
once with the same warning.

Chosen over spawning the install: boot keeps installing plugins before the
first turn, as today, and the diff is one Instant threaded through the three
call sites. docs/turn-loop/config.md states the 2 minute and 4 minute bounds.

docs/turn-loop/config.md

@@ -202,7 +202,12 @@ services.hyperhive.agent.claudePluginsAutoUpdate = false;               # defaul
 - **`claudePlugins`** — list of plugin specs passed to
   `claude plugin install <spec>`. The harness installs each spec on
   every boot, assuming `install` is idempotent; failures log a warning
-  but don't abort boot. Defaults to Anthropic's `skill-creator` (so every
+  but don't abort boot. Boot waits for the
+  marketplace adds, the optional update and the installs (serial
+  `claude plugin` calls): each call is killed and logged if it has not
+  exited within 2 minutes, and the whole sequence is capped at 4 minutes,
+  after which the remaining calls fail at once with the same warning and the
+  web UI starts. Defaults to Anthropic's `skill-creator` (so every
   agent can author, refine, and evaluate its own skills) plus
   hyperhive's own `base` plugin — skills that apply to every agent
   regardless of role (currently just `state-hygiene`) — all without