fix: error on unknown flags in call command

[beverm2391]

Problem

Unknown flags passed to the call command were silently treated as positional arguments and mapped to tool parameters via hydratePositionalArguments. This caused confusing behavior where:

mcporter call server.tool --source import

Would result in {"includeStarted": "import"} being sent to the tool (mapping import to the first tool parameter), causing validation errors that were hard to debug.

Solution

Added a check in parseCallArguments to detect unknown -- prefixed flags before they get pushed to the positional array. Now it throws a helpful CliUsageError with suggestions:

[mcporter] Unknown flag '--source' passed to call command.
If you intended to pass a tool argument, use 'source=<value>' or --args '{"source": ...}'.
Run 'mcporter call --help' to see available flags.

Testing

• All 377 existing tests pass
• Manually verified that:
  • Unknown flags now error with helpful message
  • Valid calls still work
  • key=value style arguments work
  • --args '{...}' style arguments work