feat(pre-2.1.0): demo data overhaul, examples, migration guides, install script

Pre-2.1.0 adoption polish delivering all four milestones:

A) Demo Data Overhaul — seed_demo.sql rewritten with 35 certs across
   5 issuers, 8 agents, 8 targets, 50+ jobs spanning 90 days, 55+
   audit events, discovery scans, network scan targets, S/MIME cert.

B) Examples Directory — 5 turnkey docker-compose configs:
   acme-nginx, acme-wildcard-dns01, private-ca-traefik,
   step-ca-haproxy, multi-issuer.

C) Migration Guides — migrate-from-certbot.md,
   migrate-from-acmesh.md, certctl-for-cert-manager-users.md.

D) Agent Install Script — install-agent.sh with cross-platform
   support (Linux systemd + macOS launchd), release.yml updated
   for 6-target cross-compilation.

Triple-audited against codebase: 22 factual corrections applied
across docs, examples, and config (env var names, CLI flags, ports,
DNS hook interface, scheduler loop counts, license conversion date).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/certctl-for-cert-manager-users.md

@@ -0,0 +1,143 @@
+# certctl for cert-manager Users
+
+You run cert-manager inside Kubernetes and it works well for in-cluster certificates. But you also have VMs, bare-metal servers, network appliances, and legacy systems outside the cluster. cert-manager can't reach those. This guide shows how certctl complements cert-manager to give you unified certificate visibility and automation across your entire infrastructure.
+
+## Not a Replacement
+
+cert-manager is the right tool for in-cluster certs. It's tightly integrated with Kubernetes:
+- Native CRDs (Certificate, ClusterIssuer, Issuer)
+- Automatic cert injection into Ingress and Service objects
+- Controller-driven renewal within the cluster
+
+**certctl does not replace this.** Instead, it extends your certificate management to everything outside Kubernetes: VMs, bare metal, network appliances, Windows servers, and legacy systems.
+
+## The Problem
+
+Your setup:
+- **cert-manager**: handles all certs in Kubernetes (TLS for Ingress, service-to-service, internal services)
+- **Everything else**: NGINX/Apache on VMs, HAProxy load balancers on bare metal, network appliances, Windows servers with IIS — these are managed inconsistently. Maybe Certbot cron jobs, maybe manual renewal, maybe deprecated cert files sitting around.
+
+Result:
+- No unified visibility — you don't know when non-Kubernetes certs expire
+- Renewal failures go unnoticed until the cert is already expired
+- Audit trail fragmented across multiple tools
+- Scaling to hundreds of machines becomes impossible
+
+## The Solution
+
+Deploy certctl control plane once (Docker Compose, Kubernetes Helm chart, or self-hosted). Deploy agents on your VMs, bare metal, and network appliances. One dashboard shows:
+- **All cert-manager certs** via discovery scanning (agents find cert-manager-issued certs copied to target machines, or scan the cluster directly)
+- **All certctl-managed certs** issued by shared issuers (ACME, step-ca, Vault PKI (coming in v2.1), private CA)
+- **Unified renewal and deployment** across both worlds
+- **Single pane of glass** with expiration timeline, renewal status, deployment verification, audit trail
+
+## How to Set Up
+
+### 1. Install certctl Control Plane
+
+**Option A: Docker Compose** (quickest for evaluation)
+```bash
+cd /opt/certctl
+docker compose up -d
+# Dashboard: http://localhost:3000
+# API: http://localhost:8080
+```
+
+**Option B: Kubernetes** (recommended for prod)
+```bash
+helm install certctl deploy/helm/certctl/ \
+  --set auth.apiKey=YOUR_SECURE_KEY
+```
+
+### 2. Deploy Agents to Non-Kubernetes Infrastructure
+
+On each VM, bare-metal server, or appliance (via proxy agent):
+```bash
+# Linux amd64
+curl -sSL https://github.com/shankar0123/certctl/releases/download/v2.1.0/certctl-agent-linux-amd64 \
+  -o /usr/local/bin/certctl-agent
+chmod +x /usr/local/bin/certctl-agent
+
+# Config
+sudo tee /etc/certctl/agent.env > /dev/null <<EOF
+CERTCTL_SERVER_URL=https://certctl-control-plane:8080
+CERTCTL_API_KEY=your-api-key
+CERTCTL_DISCOVERY_DIRS=/etc/nginx/certs,/etc/ssl,/etc/letsencrypt/live
+CERTCTL_KEY_DIR=/var/lib/certctl/keys
+EOF
+sudo chmod 600 /etc/certctl/agent.env
+
+# Start
+sudo systemctl start certctl-agent
+```
+
+### 3. Enable Discovery Scanning
+
+Agents scan configured directories and report back all existing certs. In the dashboard:
+- **Discovery** page: all found certs grouped by agent
+- Claim cert-manager certs to link them with Kubernetes metadata
+- Dismiss obsolete certs
+
+### 4. Configure Shared Issuers
+
+Set up the same issuer certctl uses for non-Kubernetes certs:
+- **ACME** (Let's Encrypt, for public certs)
+- **step-ca** (Smallstep, for internal certs)
+- **Vault PKI** (coming in v2.1) (HashiCorp Vault, for enterprise PKI)
+- **Private CA** (your own internal root CA)
+
+No new CA infrastructure needed. If cert-manager already uses your CA, certctl points to the same one.
+
+### 5. Create Policies for Non-Kubernetes Certs
+
+Go to **Policies** → **New Policy**:
+- Issuer: shared (ACME, step-ca, Vault (coming in v2.1), private CA)
+- Profile: serverAuth for NGINX/Apache/HAProxy, clientAuth for mTLS, emailProtection for S/MIME
+- Renewal Threshold: 30 days (default, adjust per SLA)
+- Scope: agent groups (VMs, bare metal, appliances)
+
+### 6. View Unified Inventory
+
+**Dashboard** shows:
+- Certificate status heatmap (all 1000 certs: cert-manager + certctl)
+- Renewal job trends (both types)
+- Expiration timeline (30/60/90 days)
+- Agent fleet status (all infrastructure)
+
+**Certificates** page filters by issuer (show me all ACME certs, or all step-ca certs):
+- cert-manager certs discovered from Kubernetes nodes
+- certctl-managed certs on VMs
+- Network appliance certs auto-discovered
+
+## Shared Infrastructure
+
+If cert-manager and certctl both use the same CA:
+- **ACME**: cert-manager uses ClusterIssuer + certctl uses ACME connector → same Let's Encrypt account, transparent coexistence
+- **step-ca**: cert-manager uses external issuer CRD + certctl uses step-ca connector → same provisioner, shared certificate inventory
+- **Vault PKI** (coming in v2.1): cert-manager uses external issuer CRD + certctl uses Vault connector → same mount, same audit trail
+
+No conflict. They just issue certs through the same CA. certctl's discovery scanning finds cert-manager-issued certs and shows them alongside certctl-managed ones.
+
+## Key Differences from cert-manager
+
+| Feature | cert-manager | certctl |
+|---------|--------------|---------|
+| Target | In-cluster (Kubernetes) | Out-of-cluster (VMs, bare metal, appliances) |
+| Configuration | CRDs (Certificate, ClusterIssuer, Issuer) | API + Dashboard (JSON REST) |
+| Deployment | Injected into Secret objects, mounted by pods | Agent pulls work, deploys via target-specific API (file, service restart, proxy agent) |
+| Renewal | Controller watches Certificate CRDs, triggers renewal when needed | Scheduler checks thresholds, agents poll for work |
+| Audit | Kubernetes event log | Immutable append-only audit trail |
+| Visibility | Per-namespace, per-resource | Fleet-wide, unified inventory |
+
+## Future Integration
+
+On the roadmap (V4): **cert-manager external issuer** — certctl acts as a ClusterIssuer backend for Kubernetes. This would allow cert-manager to request certificates from certctl, which could issue them via any of its connectors (step-ca, Vault, private CA, etc.). Pure integration play; no breaking changes.
+
+For now: cert-manager handles Kubernetes, certctl handles everything else. They coexist seamlessly.
+
+## Next Steps
+
+1. Review [Quick Start](./quickstart.md) for a 5-minute demo
+2. Explore [Agents and Targets](./architecture.md#agents-and-targets) for deployment architecture
+3. Read about [Discovery Scanning](./quickstart.md#discovery) to auto-find certs
+4. Check [Helm Chart](../deploy/helm/certctl/) for production Kubernetes deployment