feat: remove retired Lucy model IDs

[AdirAmsalem]

Summary

• remove retired Lucy 2 IDs from the Swift SDK model enums/definitions (lucy-2, lucy_2_rt, lucy-2-v2v)
• update video input routing and README examples to use lucy-2.1

Test plan

• git diff --check
• swift build not run: swift is not installed in this environment

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Note

Medium Risk
This is a breaking API change for clients still compiling against the removed lucy-2 enum cases/aliases. Runtime risk is low since it primarily deletes retired model identifiers and updates mappings/docs to supported replacements.

Overview
Removes the retired lucy-2 model identifiers from the public Swift SDK surface: RealtimeModel.lucy2, VideoModel.lucy2, and the deprecated aliases lucy_2_rt / lucy_2_v2v, along with their Models.realtime/Models.video definitions and allCases entries.

Updates model routing and docs/examples to stop referencing the removed IDs (e.g., ModelsInputFactory.videoInputType and the README video-edit example now use lucy-2.1), and adjusts the sample app preset mapping accordingly.

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