feat(init): interactive remote pre-staging via ssh-copy-id

orca init now interactively prompts for remote host addresses and runs
ssh-copy-id automatically (password prompt passes through to the
operator). This makes orca init the single entry point — no manual
pre-staging of SSH keys required.

- Interactive: enter host addresses (one per line, empty line to finish)
- ssh-copy-id deploys the orca public key to each host
- Skipped in --json mode (non-interactive)
- Idempotent: re-running init can stage additional hosts

Also fixed: install.sh defaults to /usr/local/bin (on PATH for all users).
Non-root without sudo falls back to ~/.local/bin + auto-adds to .bashrc.

internal/cli/init.go

@@ -5,15 +5,15 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"fmt"
+	"bufio"
 	"os"
+	"strings"
+	"os/exec"
 	"path/filepath"
 	"time"
-
 	"github.com/google/uuid"
-
 	"golang.org/x/crypto/ssh"
 	"github.com/spf13/cobra"
-
 	"git.cloudinit.dev/coreci/orca/internal/acl"
 	"git.cloudinit.dev/coreci/orca/internal/certpaths"
 	"git.cloudinit.dev/coreci/orca/internal/identity"
@@ -63,8 +63,7 @@ func runInit(out interface{ Write([]byte) (int, error) }) error {
 		Database        string       `json:"database"`
 		CAFingerprint   string       `json:"ca_fingerprint,omitempty"`
 		CertFingerprint string       `json:"cert_fingerprint,omitempty"`
-		OS              string       `json:"os"
-	"path/filepath"`
+		OS              string       `json:"os"`
 		NodeID          string       `json:"node_id"`
 		NodeName        string       `json:"node_name"`
 		Steps           []stepResult `json:"steps"`
@@ -158,8 +157,50 @@ func runInit(out interface{ Write([]byte) (int, error) }) error {
 	summary.Steps = append(summary.Steps, stepResult{Label: "ssh-key", Status: "ok", Detail: sshKeyFp[:min(16, len(sshKeyFp))] + "..."})
 	if !jsonOutput {
 		fmt.Fprintf(out, "\xe2\x9c\x93 SSH keypair provisioned: fp=%s\n", sshKeyFp[:min(16, len(sshKeyFp))]+"...")
-		fmt.Fprintf(out, "\n  To onboard remote nodes, deploy the orca public key first:\n")
-		fmt.Fprintf(out, "  ssh-copy-id -i %s root@<remote-host>\n\n", certpaths.SSHPubPath())
+	}
+
+	// Step 4a-2: Interactively pre-stage the orca public key on remote
+	// hosts (ssh-copy-id). Skipped in --json mode (non-interactive).
+	// The operator enters host addresses (one per line, empty line to
+	// finish). For each host, ssh-copy-id is run; if SSH key auth is
+	// not yet established, ssh-copy-id prompts for the password
+	// interactively. This makes orca init the single entry point —
+	// no manual pre-staging required.
+	if !jsonOutput {
+		pubPath := certpaths.SSHPubPath()
+		fmt.Fprintf(out, "\n  Pre-stage the orca public key on remote nodes.\n")
+		fmt.Fprintf(out, "  Enter host addresses (one per line, empty line to skip):\n")
+		stagedHosts := []string{}
+		reader := bufio.NewReader(os.Stdin)
+		for {
+			fmt.Fprintf(out, "  host> ")
+			line, err := reader.ReadString('\n')
+			if err != nil {
+				break
+			}
+			host := strings.TrimSpace(line)
+			if host == "" {
+				break
+			}
+			// Run ssh-copy-id interactively (password prompt passes through).
+			fmt.Fprintf(out, "  Deploying orca key to %s...\n", host)
+			cmd := exec.Command("ssh-copy-id", "-i", pubPath, "-o", "StrictHostKeyChecking=accept-new", "root@"+host)
+			cmd.Stdin = os.Stdin
+			cmd.Stdout = os.Stdout
+			cmd.Stderr = os.Stderr
+			if err := cmd.Run(); err != nil {
+				fmt.Fprintf(out, "  \xe2\x9a\xa0 Failed to deploy key to %s: %v\n", host, err)
+				continue
+			}
+			fmt.Fprintf(out, "  \xe2\x9c\x93 Key deployed to %s\n", host)
+			stagedHosts = append(stagedHosts, host)
+		}
+		if len(stagedHosts) > 0 {
+			summary.Steps = append(summary.Steps, stepResult{Label: "pre-stage", Status: "ok", Detail: strings.Join(stagedHosts, ", ")})
+		} else {
+			summary.Steps = append(summary.Steps, stepResult{Label: "pre-stage", Status: "skipped", Detail: "no hosts entered"})
+		}
+		fmt.Fprintf(out, "\n")
 	}
 
 	// Step 4b: known_hosts file (empty, 0600). Without this, the TOFU