feat(nodes): SSH bootstrap + housekeeping — install script, bundled binaries, auto-prune (#50)

* feat(nodes): SSH bootstrap + housekeeping — install script, bundled binaries, auto-prune

- `containr nodes add <user@host>` mints an enroll token, SSHes once,
  runs the install script remotely; --print emits the one-liner
- Public /api/agents/install.sh + /api/agents/download/{platform};
  agent binaries built into the image under /agents
- Agent-side `prune` (bounded docker system prune, volumes opt-in)
  and `system_df` commands
- node_agents.auto_prune + health sweep enqueues daily prune;
  offline/online transitions notify admins
- CLI nodes update/prune/commands + MCP tools (prune confirm-gated)
- Usage page: install one-liner, per-node Prune + auto toggle

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* feat(nodes): node detail page — telemetry, containers, commands, controls

/nodes/:id (admin): cpu/mem sparklines from heartbeat history
(1h/24h/7d), containers on node, command history, inline rename,
auto-prune toggle, prune-now with volume opt-in, remove. Agent rows
on the Usage page link into it.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* feat(nodes): mesh awareness + node detail page

- agent reports tailscale/netbird/zerotier/wireguard interface IPs at
  register (authoritative — absent interfaces clear stored state)
- backend stores under node_agents.metadata.mesh, merged on re-register
- node detail page shows mesh addresses under the primary IP

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/internal/api/assets/install-agent.sh

@@ -0,0 +1,82 @@
+#!/usr/bin/env bash
+# Containr node agent installer.
+#   curl -fsSL <api>/api/agents/install.sh | bash -s -- --url <api> --token <enroll-token>
+#
+# One-shot: downloads the agent binary from the Containr instance (or GH
+# releases as fallback), writes a systemd unit, starts it. SSH is never
+# needed again — the agent heartbeats and polls commands outbound.
+set -euo pipefail
+
+API_URL=""
+TOKEN=""
+AGENT_NAME=""
+VERSION=""
+
+while [ $# -gt 0 ]; do
+  case "$1" in
+    --url) API_URL="$2"; shift 2 ;;
+    --token) TOKEN="$2"; shift 2 ;;
+    --name) AGENT_NAME="$2"; shift 2 ;;
+    --version) VERSION="$2"; shift 2 ;;
+    *) echo "unknown flag: $1" >&2; exit 2 ;;
+  esac
+done
+
+[ -n "$API_URL" ] || { echo "--url is required" >&2; exit 2; }
+[ -n "$TOKEN" ] || { echo "--token is required (create one: containr nodes tokens create)" >&2; exit 2; }
+API_URL="${API_URL%/}"
+API_URL="${API_URL%/api/v1}"
+API_URL="${API_URL%/api}"
+
+info() { printf '\033[1;34m==>\033[0m %s\n' "$*"; }
+err()  { printf '\033[1;31mError:\033[0m %s\n' "$*" >&2; }
+
+[ "$(id -u)" = "0" ] || { err "run as root (sudo bash -s -- --url … --token …)"; exit 1; }
+command -v docker >/dev/null 2>&1 || { err "docker not found"; exit 1; }
+command -v curl >/dev/null 2>&1 || { err "curl not found"; exit 1; }
+
+ARCH="$(uname -m)"
+case "$ARCH" in
+  x86_64|amd64) ARCH=amd64 ;;
+  aarch64|arm64) ARCH=arm64 ;;
+  *) err "unsupported architecture: $ARCH"; exit 1 ;;
+esac
+
+BIN=/usr/local/bin/containr-agent
+info "downloading containr-agent (linux/$ARCH)"
+if ! curl -fsSL "$API_URL/api/agents/download/linux-$ARCH" -o "$BIN" 2>/dev/null; then
+  info "instance has no bundled binary — trying GitHub releases"
+  REF="${VERSION:-latest}"
+  if [ "$REF" = "latest" ]; then
+    DL="https://github.com/Dvorinka/Containr/releases/latest/download/containr-agent-linux-$ARCH"
+  else
+    DL="https://github.com/Dvorinka/Containr/releases/download/$REF/containr-agent-linux-$ARCH"
+  fi
+  curl -fsSL "$DL" -o "$BIN" || { err "agent download failed"; exit 1; }
+fi
+chmod +x "$BIN"
+
+UNIT=/etc/systemd/system/containr-agent.service
+info "writing systemd unit"
+cat > "$UNIT" <<UNIT
+[Unit]
+Description=Containr node agent
+After=docker.service network-online.target
+Wants=network-online.target
+Requires=docker.service
+
+[Service]
+Environment=CONTAINR_API_URL=$API_URL
+Environment=CONTAINR_AGENT_AUTH_TOKEN=$TOKEN
+Environment=CONTAINR_AGENT_NAME=${AGENT_NAME:-$(hostname)}
+Restart=always
+RestartSec=5
+ExecStart=$BIN
+
+[Install]
+WantedBy=multi-user.target
+UNIT
+
+systemctl daemon-reload
+systemctl enable --now containr-agent
+info "agent installed and started — it should appear in Containr within ~15s"