feat(M1): Project scaffolding, DB schema, core infrastructure

- Initialize Rust workspace with 7 crates (pm-web, pm-worker, pm-core,
  pm-agent-client, pm-auth, pm-ca, pm-reports)
- React + TypeScript + Vite + MUI frontend scaffold
- Full PostgreSQL schema: all 17 tables with indexes and constraints
- pm-core: config (TOML+env), db (SQLx pool + migrations), error
  (unified AppError + JSON envelope), request_id (ULID middleware),
  logging (tracing JSON/pretty)
- pm-web: Axum skeleton, /status/health endpoint, static file serving
- pm-worker: Tokio skeleton, heartbeat writer, schema version check
- Embedded sqlx migrations with advisory lock (single-writer)
- systemd unit files, setup.sh, build-frontend.sh
- config.example.toml with all configuration keys
- docs/runbooks/restore.md
- cargo check passes with zero warnings

Closes M1.

config/config.example.toml

@@ -0,0 +1,95 @@
+# Linux Patch Manager — Example Configuration
+# Copy to /etc/patch-manager/config.toml and edit for your environment.
+#
+# Environment variable overrides follow the pattern:
+#   PATCH_MANAGER__SECTION__KEY=value
+# e.g. PATCH_MANAGER__DATABASE__URL=postgres://...
+
+# ============================================================
+# Web Server
+# ============================================================
+[server]
+# Bind address for the HTTPS listener
+host = "0.0.0.0"
+
+# HTTPS port (443 for production; 8443 for non-root dev)
+port = 443
+
+# Path to compiled React SPA static files
+static_dir = "/usr/share/patch-manager/frontend"
+
+# ============================================================
+# Database
+# ============================================================
+[database]
+# PostgreSQL connection URL
+url = "postgres://patch_manager:CHANGEME@localhost/patch_manager"
+
+# Connection pool sizing
+max_connections = 20
+min_connections = 2
+
+# Seconds to wait for a connection from the pool
+acquire_timeout_secs = 30
+
+# ============================================================
+# Background Worker
+# ============================================================
+[worker]
+# Agent health check interval (seconds). Default: 300 = 5 minutes
+health_poll_interval_secs = 300
+
+# Agent patch data poll interval (seconds). Default: 1800 = 30 minutes
+patch_poll_interval_secs = 1800
+
+# Maximum concurrent mTLS agent calls (Tokio Semaphore)
+max_concurrent_agent_calls = 64
+
+# Worker heartbeat write interval (seconds)
+heartbeat_interval_secs = 30
+
+# ============================================================
+# Logging
+# ============================================================
+[logging]
+# Log level: trace, debug, info, warn, error
+# Override with RUST_LOG environment variable
+level = "info"
+
+# Output format: "json" (production) or "pretty" (development)
+format = "json"
+
+# ============================================================
+# Security
+# ============================================================
+[security]
+# IP whitelist: list of CIDRs or individual IPs allowed to connect.
+# IMPORTANT: An empty list allows ALL IPs. Restrict this in production.
+# Example: ["10.0.0.0/8", "192.168.1.50"]
+ip_whitelist = []
+
+# Ed25519 JWT signing key (private key, PEM format)
+# Generate: openssl genpkey -algorithm ed25519 -out /etc/patch-manager/jwt/signing.pem
+jwt_signing_key_path = "/etc/patch-manager/jwt/signing.pem"
+
+# Ed25519 JWT verification key (public key, PEM format)
+# Generate: openssl pkey -in /etc/patch-manager/jwt/signing.pem -pubout -out /etc/patch-manager/jwt/verify.pem
+jwt_verify_key_path = "/etc/patch-manager/jwt/verify.pem"
+
+# JWT access token TTL in seconds (default: 900 = 15 minutes)
+jwt_access_ttl_secs = 900
+
+# mTLS client certificate for agent communication
+agent_client_cert_path = "/etc/patch-manager/certs/client.crt"
+agent_client_key_path  = "/etc/patch-manager/certs/client.key"
+
+# Internal CA certificate and private key
+# Private key has 0600 permissions; protected by hardware-host FDE
+ca_cert_path = "/etc/patch-manager/ca/ca.crt"
+ca_key_path  = "/etc/patch-manager/ca/ca.key"
+
+# Web UI TLS certificate (default: self-signed from internal CA)
+# Set web_tls_strategy = 'operator_supplied' in system_config and
+# point these paths to your certificate/key to use your own cert.
+web_tls_cert_path = "/etc/patch-manager/tls/web.crt"
+web_tls_key_path  = "/etc/patch-manager/tls/web.key"