feat(security-hardening): add SCAP-STIG compliance configuration files

Add security hardening configuration files implementing SCAP-STIG
controls:

- sysctl-hardening.conf: 75 kernel security parameters covering:
  * IP forwarding and redirect controls
  * Source routing and martian packet logging
  * TCP SYN cookies and timestamps
  * ExecShield and ASLR settings
  * Ptrace scope restrictions
  * Unprivileged BPF and userns restrictions

- security-limits.conf: Resource limits for:
  * Core dump prevention (fork bomb protection)
  * Process count limits (4096 soft, 8192 hard)
  * File handle limits (1024 soft, 4096 hard)
  * Memory lock and file size restrictions

- issue, issue.net, motd: Security warning banners for local
  and network login

- modprobe/: Directory for kernel module blacklist configurations

These configs implement CIS Benchmark and DISA STIG requirements
for Linux server hardening.

Related: KNELServerBuild/ProjectCode/Modules/Security/secharden-scap-stig.sh

initializers/security-hardening/configs/security-limits.conf

@@ -0,0 +1,29 @@
+# KNEL Security Limits Configuration
+# SCAP/STIG compliant resource limits
+
+# Prevent core dumps for all users
+* hard core 0
+* soft core 0
+
+# Prevent core dumps for root
+root hard core 0
+root soft core 0
+
+# Limit max processes for users (fork bomb protection)
+* soft nproc 4096
+* hard nproc 8192
+
+# Limit max file handles
+* soft nofile 1024
+* hard nofile 4096
+
+# Limit max memory lock
+* hard memlock 64
+
+# Limit max file size
+* soft fsize 2097152
+* hard fsize 4194304
+
+# Stack size limit
+* soft stack 8192
+* hard stack 65536