v0.3.2 - Implement -p/--port CLI option for first-time startup port override

- Add cli_options_t structure for extensible command line options
- Implement port override in create_default_config_event()
- Update main() with robust CLI parsing and validation
- Add comprehensive help text documenting first-time only behavior
- Ensure CLI options only affect initial configuration event creation
- Maintain event-based configuration architecture for ongoing operation
- Include comprehensive error handling and input validation
- Add documentation in CLI_PORT_OVERRIDE_IMPLEMENTATION.md

Tested: First-time startup uses CLI port, subsequent startups use database config

src/config.h

@@ -32,6 +32,12 @@ typedef struct {
     char config_file_path[512];  // Temporary for compatibility
 } config_manager_t;
 
+// Command line options structure for first-time startup
+typedef struct {
+    int port_override;  // -1 = not set, >0 = port value
+    // Future CLI options can be added here
+} cli_options_t;
+
 // Global configuration manager
 extern config_manager_t g_config_manager;
 
@@ -62,7 +68,7 @@ int get_config_bool(const char* key, int default_value);
 
 // First-time startup functions
 int is_first_time_startup(void);
-int first_time_startup_sequence(void);
+int first_time_startup_sequence(const cli_options_t* cli_options);
 int startup_existing_relay(const char* relay_pubkey);
 
 // Configuration application functions