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

CLI_PORT_OVERRIDE_IMPLEMENTATION.md

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+# CLI Port Override Implementation
+
+## Overview
+
+This document describes the implementation of the `-p <port>` command line option for the C Nostr Relay, which allows overriding the default relay port during first-time startup only.
+
+## Design Principles
+
+1. **First-time startup only**: Command line options only affect the initial configuration event creation
+2. **Event-based persistence**: After first startup, all configuration is managed through database events
+3. **Proper encapsulation**: All configuration logic is contained within `config.c`
+4. **Extensible design**: The CLI options structure can easily accommodate future command line options
+
+## Implementation Details
+
+### Files Modified
+
+#### `src/config.h`
+- Added `cli_options_t` structure to encapsulate command line options
+- Updated `first_time_startup_sequence()` function signature
+
+#### `src/config.c`
+- Updated `first_time_startup_sequence()` to accept CLI options parameter
+- Updated `create_default_config_event()` to accept CLI options parameter
+- Implemented port override logic in DEFAULT_CONFIG_VALUES array processing
+
+#### `src/default_config_event.h`
+- Updated function signature for `create_default_config_event()`
+- Added proper header include for `cli_options_t` definition
+
+#### `src/main.c`
+- Added command line parsing for `-p <port>` and `--port <port>`
+- Updated help text to document the new option
+- Added proper error handling for invalid port values
+- Updated function call to pass CLI options to configuration system
+
+### CLI Options Structure
+
+```c
+typedef struct {
+    int port_override;  // -1 = not set, >0 = port value
+    // Future CLI options can be added here
+} cli_options_t;
+```
+
+### Command Line Usage
+
+```bash
+# First-time startup with port override
+./c_relay_x86 -p 9090
+./c_relay_x86 --port 9090
+
+# Show help (includes new option)
+./c_relay_x86 --help
+
+# Show version
+./c_relay_x86 --version
+```
+
+### Error Handling
+
+The implementation includes robust error handling for:
+- Missing port argument: `./c_relay_x86 -p`
+- Invalid port format: `./c_relay_x86 -p invalid_port`
+- Out-of-range ports: `./c_relay_x86 -p 0` or `./c_relay_x86 -p 99999`
+
+## Behavior Verification
+
+### First-Time Startup
+When no database exists:
+1. Command line is parsed and `-p <port>` is processed
+2. CLI options are passed to `first_time_startup_sequence()`
+3. Port override is applied in `create_default_config_event()`
+4. Configuration event is created with overridden port value
+5. Relay starts on the specified port
+6. Port setting is persisted in database for future startups
+
+### Subsequent Startups
+When database already exists:
+1. Command line is still parsed (for consistency)
+2. Existing relay path is taken
+3. Configuration is loaded from database events
+4. CLI options are ignored
+5. Relay starts on port from database configuration
+
+## Testing Results
+
+### Test 1: First-time startup with port override
+```bash
+./c_relay_x86 -p 9090
+```
+**Result**: ✅ Relay starts on port 9090, configuration stored in database
+
+### Test 2: Subsequent startup ignores CLI options
+```bash
+./c_relay_x86 -p 7777
+```
+**Result**: ✅ Relay starts on port 9090 (from database), ignores `-p 7777`
+
+### Test 3: Error handling
+```bash
+./c_relay_x86 -p invalid_port
+./c_relay_x86 -p
+```
+**Result**: ✅ Proper error messages and help text displayed
+
+### Test 4: Help text
+```bash
+./c_relay_x86 --help
+```
+**Result**: ✅ Displays updated help with `-p, --port PORT` option
+
+## Database Verification
+
+The port setting is correctly stored in the database:
+```sql
+SELECT json_extract(tags, '$') FROM events WHERE kind = 33334;
+```
+Shows the overridden port value in the configuration event tags.
+
+## Future Extensions
+
+The `cli_options_t` structure is designed to be easily extended:
+
+```c
+typedef struct {
+    int port_override;        // -1 = not set, >0 = port value
+    char* description_override; // Future: relay description override
+    int max_connections_override; // Future: connection limit override
+    // Add more options as needed
+} cli_options_t;
+```
+
+## Key Design Benefits
+
+1. **Separation of Concerns**: Main function handles CLI parsing, config system handles application
+2. **First-time Only**: Prevents confusion about configuration precedence
+3. **Event-based Architecture**: Maintains consistency with the relay's event-based configuration system
+4. **Extensible**: Easy to add new command line options in the future
+5. **Robust**: Comprehensive error handling and validation
+6. **Documented**: Clear help text explains behavior to users
+
+## Summary
+
+The `-p <port>` command line option implementation successfully provides a way to override the default relay port during first-time startup while maintaining the event-based configuration architecture for ongoing operation. The implementation is robust, well-tested, and ready for production use.