docs: remove duplicate H1 where frontmatter title already sets it

docs/nodes/index.md

@@ -7,8 +7,6 @@ read_when:
 title: "Nodes"
 ---
 
-# Nodes
-
 A **node** is a companion device (macOS/iOS/Android/headless) that connects to the Gateway **WebSocket** (same port as operators) with `role: "node"` and exposes a command surface (e.g. `canvas.*`, `camera.*`, `device.*`, `notifications.*`, `system.*`) via `node.invoke`. Protocol details: [Gateway protocol](/gateway/protocol).
 
 Legacy transport: [Bridge protocol](/gateway/bridge-protocol) (TCP JSONL;

docs/nodes/talk.md

@@ -6,8 +6,6 @@ read_when:
 title: "Talk Mode"
 ---
 
-# Talk Mode
-
 Talk mode is a continuous voice conversation loop:
 
 1. Listen for speech

docs/nodes/troubleshooting.md

@@ -6,8 +6,6 @@ read_when:
 title: "Node Troubleshooting"
 ---
 
-# Node troubleshooting
-
 Use this page when a node is visible in status but node tools fail.
 
 ## Command ladder