feat: add node control API for starting/stopping peers via SSH

New endpoints on master node:
- POST /api/nodes/<id>/start - Start rf-mapper on peer
- POST /api/nodes/<id>/stop - Stop rf-mapper on peer
- POST /api/nodes/<id>/restart - Restart rf-mapper on peer
- GET /api/nodes/<id>/status - Check peer status

Uses SSH with scanner_id as hostname (relies on ~/.ssh/config).
Enables Home Assistant integration to control peer nodes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/rf_mapper/web/app.py

@@ -2,6 +2,7 @@
 
 import json
 import os
+import subprocess
 import threading
 import time
 from datetime import datetime
@@ -1598,6 +1599,130 @@ def create_app(config: Config | None = None) -> Flask:
         else:
             return jsonify({"error": "Peer not found"}), 404
 
+    # ==================== Node Control API ====================
+
+    def _ssh_node_command(scanner_id: str, command: str, timeout: int = 30) -> tuple[bool, str]:
+        """Execute a command on a peer node via SSH.
+
+        Uses scanner_id as SSH hostname (relies on ~/.ssh/config for ports).
+
+        Returns:
+            Tuple of (success, output/error message)
+        """
+        try:
+            result = subprocess.run(
+                ["ssh", "-o", "ConnectTimeout=5", "-o", "BatchMode=yes",
+                 scanner_id, command],
+                capture_output=True,
+                text=True,
+                timeout=timeout
+            )
+            output = result.stdout.strip() or result.stderr.strip()
+            return result.returncode == 0, output
+        except subprocess.TimeoutExpired:
+            return False, "SSH command timed out"
+        except Exception as e:
+            return False, str(e)
+
+    @app.route("/api/nodes/<scanner_id>/start", methods=["POST"])
+    def api_node_start(scanner_id: str):
+        """Start rf-mapper on a peer node via SSH"""
+        rf_config = app.config["RF_CONFIG"]
+        if not rf_config.scanner.is_master:
+            return jsonify({"error": "Only master node can control peers"}), 403
+
+        db = app.config.get("DATABASE")
+        if db:
+            peer = db.get_peer(scanner_id)
+            if not peer:
+                return jsonify({"error": f"Unknown peer: {scanner_id}"}), 404
+
+        print(f"[Node] Starting rf-mapper on {scanner_id}...")
+        cmd = "cd ~/git/rf-mapper && source venv/bin/activate && rf-mapper start"
+        success, output = _ssh_node_command(scanner_id, cmd, timeout=60)
+
+        if success:
+            print(f"[Node] {scanner_id} started successfully")
+            return jsonify({"status": "started", "scanner_id": scanner_id, "output": output})
+        else:
+            print(f"[Node] Failed to start {scanner_id}: {output}")
+            return jsonify({"error": "Failed to start", "details": output}), 500
+
+    @app.route("/api/nodes/<scanner_id>/stop", methods=["POST"])
+    def api_node_stop(scanner_id: str):
+        """Stop rf-mapper on a peer node via SSH"""
+        rf_config = app.config["RF_CONFIG"]
+        if not rf_config.scanner.is_master:
+            return jsonify({"error": "Only master node can control peers"}), 403
+
+        db = app.config.get("DATABASE")
+        if db:
+            peer = db.get_peer(scanner_id)
+            if not peer:
+                return jsonify({"error": f"Unknown peer: {scanner_id}"}), 404
+
+        print(f"[Node] Stopping rf-mapper on {scanner_id}...")
+        cmd = "cd ~/git/rf-mapper && source venv/bin/activate && rf-mapper stop"
+        success, output = _ssh_node_command(scanner_id, cmd, timeout=30)
+
+        if success:
+            print(f"[Node] {scanner_id} stopped successfully")
+            return jsonify({"status": "stopped", "scanner_id": scanner_id, "output": output})
+        else:
+            print(f"[Node] Failed to stop {scanner_id}: {output}")
+            return jsonify({"error": "Failed to stop", "details": output}), 500
+
+    @app.route("/api/nodes/<scanner_id>/restart", methods=["POST"])
+    def api_node_restart(scanner_id: str):
+        """Restart rf-mapper on a peer node via SSH"""
+        rf_config = app.config["RF_CONFIG"]
+        if not rf_config.scanner.is_master:
+            return jsonify({"error": "Only master node can control peers"}), 403
+
+        db = app.config.get("DATABASE")
+        if db:
+            peer = db.get_peer(scanner_id)
+            if not peer:
+                return jsonify({"error": f"Unknown peer: {scanner_id}"}), 404
+
+        print(f"[Node] Restarting rf-mapper on {scanner_id}...")
+        cmd = "cd ~/git/rf-mapper && source venv/bin/activate && rf-mapper restart"
+        success, output = _ssh_node_command(scanner_id, cmd, timeout=60)
+
+        if success:
+            print(f"[Node] {scanner_id} restarted successfully")
+            return jsonify({"status": "restarted", "scanner_id": scanner_id, "output": output})
+        else:
+            print(f"[Node] Failed to restart {scanner_id}: {output}")
+            return jsonify({"error": "Failed to restart", "details": output}), 500
+
+    @app.route("/api/nodes/<scanner_id>/status", methods=["GET"])
+    def api_node_status(scanner_id: str):
+        """Get rf-mapper status on a peer node via SSH"""
+        rf_config = app.config["RF_CONFIG"]
+        if not rf_config.scanner.is_master:
+            return jsonify({"error": "Only master node can control peers"}), 403
+
+        db = app.config.get("DATABASE")
+        if db:
+            peer = db.get_peer(scanner_id)
+            if not peer:
+                return jsonify({"error": f"Unknown peer: {scanner_id}"}), 404
+
+        cmd = "cd ~/git/rf-mapper && source venv/bin/activate && rf-mapper status"
+        success, output = _ssh_node_command(scanner_id, cmd, timeout=15)
+
+        # Parse status from output
+        reachable = success or "not running" in output.lower()
+        running = success and "running" in output.lower() and "not running" not in output.lower()
+
+        return jsonify({
+            "scanner_id": scanner_id,
+            "reachable": reachable,
+            "running": running,
+            "output": output
+        })
+
     @app.route("/api/sync/devices", methods=["GET"])
     def api_sync_devices_get():
         """Get devices for sync (called by peers)"""