feat(enrollment): implement token-based enrollment flow

Changes:
1. ✅ Updated SHA256SUMS with new ostp-server binary
2. ✅ Made oncp-master optional in deploy.sh (two deployment modes)
3. ✅ Added enrollment_token support to ostp-server
4. ✅ Updated config examples with token field

Deployment Modes:
- Mode 1 (Standalone): Connect to existing master with enrollment token
- Mode 2 (Full Stack): Deploy both master + server on one host

ostp-server Enrollment Flow:
1. Admin generates token on master: \oncp-master node token --expiry 60\
2. Node submits enrollment with token in config (psk: 'AUTO')
3. Master validates token (silent drop if invalid - security)
4. Admin approves node: \oncp-master node approve <node-id>\
5. Node receives PSK + IP from 10.X.0.0/16 pool
6. Update config with PSK, restart server

deploy.sh Features:
- Interactive mode selection
- Conditional oncp-master installation
- Automated token generation (full stack mode)
- Enrollment submission (standalone mode)

Config Examples:
- server.json.example: Full stack with local master
- server-enrollment.json.example: Standalone with token

Security:
- Token validation before enrollment acceptance
- Silent drop on invalid token (prevents enumeration)
- One-time use tokens with expiration
- IPAM automatic IP allocation from pool

Documentation:
- Updated README with deployment modes
- Added enrollment workflow explanation
- Security features documented
- CLI examples for both modes

dist/linux-x64/SHA256SUMS

@@ -1,3 +1,3 @@
-cf3996eac77ed62d184452b3032e3bffc60c120e77cee57899a33893322b0cc4  ostp-client-linux
-d3ec5b5ee8c90f1f92667458f44a795159157ae64e8d5073888838fbfce286e2  ostp-server
+d9306f297f1b4558169098acd07fb455352fe198715b89064f20955371671eee  ostp-server
 53de7690ddcd22828d1d2c55bec75e7a43aa6476827d8162615549b08a1a39dc  oncp-master
+cf3996eac77ed62d184452b3032e3bffc60c120e77cee57899a33893322b0cc4  ostp-client-linux