docs(web-ui): update reading path to point at terminal-rendering.md

The 'How does the per-agent terminal render tool calls?' reading path
was pointing only at web-ui/agent.md. terminal-rendering.md is the
authoritative reference (added recently with the full row taxonomy
table). Update the pointer to send readers there first, with a
note that web-ui/agent.md has the high-level summary.

docs/web-ui.md

@@ -37,7 +37,9 @@ This doc has been split for readability. Pick the section you need:
   [`web-ui/dashboard.md`](web-ui/dashboard.md) (Dashboard
   endpoints, Dashboard event channel).
 - **"How does the per-agent terminal render tool calls?"** →
-  [`web-ui/agent.md`](web-ui/agent.md) (Live view).
+  [`terminal-rendering.md`](terminal-rendering.md) (full row
+  taxonomy + dispatch walkthrough); for a high-level summary see
+  [`web-ui/agent.md`](web-ui/agent.md) (Per-stream rendering).
 - **"What slash commands does the agent accept?"** →
   [`web-ui/agent.md`](web-ui/agent.md) (Terminal-embedded prompt).
 - **"What are the per-agent HTTP endpoints?"** →