Update routing docs & tieline creation

[andrew-welker]

This pull request introduces significant improvements to the connection-based routing system, focusing on how tie lines and signal types are handled, validated, and documented. The changes enhance both the routing algorithm and configuration validation, making routing more robust and flexible. The documentation is also updated to clearly explain these new behaviors and best practices.

Routing algorithm and signal type handling:

• Routing now supports multiple distinct signal types (audio, video, audioVideo, secondaryAudio, usbInput, usbOutput), and combined types like audioVideo are automatically split into separate routing operations for each signal. The routing algorithm only considers tie lines compatible with the requested signal type, ensuring correct and flexible path discovery. [1] [2] [3]
• The system supports port-specific routing, and all routing requests are queued to handle device state transitions (e.g., warming/cooling).

Tie line configuration and validation:

• Tie line type is now determined as the intersection of signal types supported by both source and destination ports, unless a type override is specified in configuration. This ensures only compatible signals are routed. [1] [2] [3] [4] [5]
• Configuration validation is improved: at startup, tie lines are checked to ensure both ports exist, have at least one common signal type, and that any override type is supported by both ports. Invalid configurations are rejected with clear error messages. [1] [2]

Documentation updates:

• The technical documentation is updated to explain the new signal type handling, tie line type determination, validation logic, and configuration examples (including both valid and invalid cases). This provides clear guidance for system integrators and developers. [1] [2] [3] [4]

These changes collectively make the routing system more reliable, easier to configure correctly, and better documented for future users and maintainers.

• docs: udpate routing documentation to match the algorithm
• fix: restrict tieline creation when signal types are invalid

[Copilot]

Pull request overview

This PR updates the connection-based routing documentation to reflect the current signal-type handling behavior, and tightens tie line creation to prevent building tie lines when port signal types are incompatible.

Changes:

• Updated tie line type documentation to describe intersection-based signal type calculation and override behavior.
• Changed TieLine.Type to use the intersection of source/destination port signal types (unless overridden).
• Added signal type compatibility validation during TieLineConfig.GetTieLine() creation.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/PepperDash.Essentials.Core/Routing/TieLineConfig.cs	Adds signal-type compatibility validation before creating tie lines; updates OverrideType docstring.
src/PepperDash.Essentials.Core/Routing/TieLine.cs	Changes tie line effective signal type to source/destination intersection; updates XML docs accordingly.
docs/docs/technical-docs/Connection-Based-Routing.md	Expands routing docs to describe signal splitting/filtering and tie line type determination/validation.

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