Initial implementation of google-dialog

[pragmatrix]

This PR uses the Gemini Live API to implement a Google based live dialog option for the context switch protocol and audio knife.

[Copilot]

Pull request overview

Adds a new “google-dialog” service backed by the Gemini Live API, wiring it into the context-switch registry and updating examples to support multiple live dialog providers (OpenAI, Azure OpenAI, Google).

Changes:

• Introduces services/google-dialog (params/events + client session loop) and registers it under "google-dialog".
• Refactors examples/dialog.rs into a provider-based CLI with model/voice listing and shared function-call handling.
• Adjusts context-switch-core exports and performs repo-wide import cleanups; adds the gemini-live-rs submodule + related workspace dependencies.

Reviewed changes

Copilot reviewed 38 out of 38 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/tests.rs	Import path cleanup to match new context_switch_core re-exports.
src/protocol.rs	Updates imports for BillingId/RequestId after core export changes.
src/lib.rs	Re-exports GoogleDialog from the top-level services module.
src/context_switch.rs	Registers "google-dialog" service and minor comment touch-up.
services/playback/src/lib.rs	Import cleanup and minor anyhow usage refactor.
services/openai-dialog/src/lib.rs	Import cleanup to use top-level Conversation.
services/openai-dialog/src/client.rs	Import regrouping; no logic change.
services/google-transcribe/src/transcribe.rs	Import cleanup and uses ConversationOutput directly.
services/google-dialog/src/types.rs	Adds Google dialog params + service event types.
services/google-dialog/src/lib.rs	Adds GoogleDialog service entrypoint and output-modality parsing.
services/google-dialog/src/client.rs	Implements Gemini Live session loop, IO/event handling, and billing mapping.
services/google-dialog/Cargo.toml	New crate manifest for google-dialog.
services/elevenlabs/src/transcribe.rs	Import cleanup; extracts language helpers import.
services/azure/src/translate.rs	Import cleanup to use re-exported core types.
services/azure/src/transcribe.rs	Import cleanup to use re-exported core types.
services/azure/src/synthesize.rs	Import cleanup to use re-exported core types.
services/aristech/src/transcribe.rs	Import cleanup to use re-exported core types.
services/aristech/src/synthesize.rs	Import cleanup to use re-exported core types.
examples/transcribe.rs	Updates imports to new context_switch_core re-exports.
examples/dialog.rs	New provider-based CLI and refactored conversation/playback wiring.
examples/dialog_providers/openai.rs	Provider implementation + OpenAI model listing helper.
examples/dialog_providers/mod.rs	Provider API trait + dispatcher.
examples/dialog_providers/google.rs	Provider implementation + Gemini model listing + voice validation.
examples/dialog_providers/azure_openai.rs	Provider implementation for Azure OpenAI (deployment-based).
examples/azure-translate.rs	Import cleanup to new context_switch_core re-exports.
examples/aristech-transcribe.rs	Import cleanup; adds a spellcheck ignore comment.
examples/aristech-synthesize.rs	Import cleanup; minor reordering.
core/src/lib.rs	Makes conversation module private and re-exports conversation types at crate root.
core/src/conversation.rs	Fixes comment wording (“its” → “it’s”).
core/src/billing_context.rs	Import formatting cleanup.
Cargo.toml	Adds google-dialog/gemini-live wiring, submodule deps, and workspace metadata.
audio-knife/src/main.rs	Import cleanup to new BillingId re-export.
.vscode/settings.json	Removes VS Code spellchecker settings file.
.harper-dictionary.txt	Updates spelling dictionary entries (e.g., alsa, inband).
.gitmodules	Adds external/gemini-live-rs submodule entry.
.github/copilot-instructions.md	Adds/expands repo coding guidelines.
.env.example	Adds GEMINI_API_KEY example entry.