Extend configuration file support with timing and performance settings:

- base_broadcast_interval, idle_broadcast_interval, dirty_threshold
- client_timeout, cleanup_interval, device_id_expiry_time
- status_log_interval, main_loop_sleep, poll_timeout

NetSyncServer now accepts a ServerConfig object and uses timing values
from configuration instead of class constants. Backward compatibility
is maintained when config is not provided.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Extend configuration with NetworkVariable limit and monitoring settings:

- max_global_vars, max_client_vars: Variable count limits
- max_var_name_length, max_var_value_length: Size limits
- nv_flush_interval: Flush cadence configuration
- nv_monitor_window_size, nv_monitor_threshold: Monitoring settings

NetSyncServer now reads NV limits and monitoring parameters from config.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Extend configuration with internal system limits:

- max_virtual_transforms: Maximum virtual transforms per client
- pub_queue_maxsize: Publisher queue size limit
- delta_ring_size: NV sync delta ring buffer size

Add set/get_max_virtual_transforms() functions to binary_serializer.py
for dynamic configuration of the virtual transform limit.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add logging section to TOML configuration with:
  - log_dir: Directory for log files (None = console only)
  - log_level_console: Console log level (default: INFO)
  - log_json_console: Enable JSON console output
  - log_rotation: Custom rotation rule (None = use internal default)
  - log_retention: Custom retention rule (None = use internal default)
- Add validation for log_level_console (must be valid log level)
- Add CLI args merging for logging settings
- Refactor main() to configure logging after config loading
  so that config file settings can be applied
- Add comprehensive tests for logging configuration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add examples/config.toml with all configurable settings
- Include comprehensive comments explaining each setting
- Show default values and usage examples
- Document configuration priority: CLI args > config file > defaults

Usage:
  styly-netsync-server --config examples/config.toml

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Change argparse default from "INFO" to None so that CLI args only
override config file values when explicitly specified by the user.

Previously, argparse default="INFO" meant args.log_level_console was
never None, so merge_cli_args always overwrote the config file value.

Add regression test to verify None CLI values preserve config settings.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Replace SystemExit(1) with typed ConfigurationError exception that
stores the list of validation errors. This allows main() to catch
validation errors specifically and print user-friendly messages.

- Add ConfigurationError class with errors attribute
- Update create_config_from_args to raise ConfigurationError
- Update main() to catch ConfigurationError and print each error
- Add tests for ConfigurationError behavior

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add get_unknown_keys() function to detect unknown sections and keys
in TOML configuration files. This helps catch typos like "log_levl_console"
that would otherwise be silently ignored.

- Add get_unknown_keys() function to detect unknown sections/keys
- Warn about unknown keys in create_config_from_args (using print()
  since logging is not yet configured at that point)
- Add comprehensive tests for unknown key detection

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Log the "Loaded configuration from" message after configure_logging()
is called, ensuring the log output uses the properly configured
logging settings rather than loguru's defaults.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add bundled default.toml with all default configuration values
- Remove hardcoded defaults from ServerConfig dataclass
- Remove DEFAULT_* global constants from server.py
- Remove _DEFAULT_* class constants from NetSyncServer
- NetSyncServer now loads default.toml when config is not provided
- Implement layered config: CLI args > user.toml > default.toml
- Rename --config to --user-config for clarity
- Add DefaultConfigError for fatal config loading failures
- Exit with error if default.toml cannot be loaded

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add ability to send RPC messages to specific client(s) by ClientNo
instead of broadcasting to all clients in the room.

Changes:
- binary_serializer.py: Add MSG_RPC_TARGETED (11), serialize/deserialize functions
- server.py: Add _get_client_identity_by_client_no() helper
- server.py: Add _send_rpc_to_clients() for ROUTER-based direct delivery
- server.py: Handle MSG_RPC_TARGETED in receive loop

Binary format for MSG_RPC_TARGETED:
[1b] type | [2b] sender | [2b] count | [2b*N] targets | [1b+N] name | [2b+N] args

Part of #239

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add ability to send RPC messages to specific client(s) by ClientNo
instead of broadcasting to all clients in the room.

Changes:
- BinarySerializer.cs: Add MSG_RPC_TARGETED (11), serialize/deserialize
- DataStructure.cs: Add RPCTargetedMessage class
- RPCManager.cs: Add SendTo() method for targeted RPC sending
- NetSyncManager.cs: Add public RpcTo() API methods
- ConnectionManager.cs: Poll DEALER socket for incoming targeted messages
- MessageProcessor.cs: Handle MSG_RPC_TARGETED in ProcessIncomingMessage

Public API:
- RpcTo(int targetClientNo, string functionName, string[] args)
- RpcTo(int[] targetClientNos, string functionName, string[] args)

Part of #239

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Add sender verification to reject RPCs from unknown identities (Server)
- Add function name length validation (max 255 bytes) to prevent overflow
- Unify logging to use argumentsJson key consistently
- Add queuing support for SendTo() when not ready (Unity)
- Add comprehensive unit tests for targeted RPC serialization
- Update README with RpcTo() API examples

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>