feat(pkg-r): Add querychat_app()

[gadenbuie]

Adds a simple chat interface via querychat_app() that lets you quickly spin up a chat around a dataset.

The simplest approach is to just pass in a dataset:

library(querychat)

mtcars |> querychat_app()

Or you can configure the chat using the ..., which are passed to querychat_init()

mtcars |> querychat_app(client = ellmer::chat_anthropic())

Or you can pass in a full querychat_init() object

querychat_config <- querychat_init(
  data_source = querychat_data_source(mtcars),
  greeting = "Hi! Ask me about the mtcars dataset.

* <span class='suggestion submit'>What is the average mpg?</span>
* <span class='suggestion submit'>Show me the top 5 cars by hp.</span>
* <span class='suggestion submit'>Show me the cars with mpg greater than 20.</span>",
  extra_instructions = "/no_think",
  client = ellmer::chat_ollama(model = "qwen3:8b"),
)

querychat_config |> querychat_app()

[Copilot]

Pull Request Overview

This PR adds a new querychat_app() function that creates a simple Shiny app for chatting with data using natural language queries. The app provides a complete interface with a sidebar chat, data dashboard, and SQL query display.

Key changes include:

• New querychat_app() function for launching a standalone Shiny app
• Refactored tool system with dedicated functions for dashboard updates and queries
• Enhanced UI components with proper HTML dependencies and JavaScript interactions

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg-r/R/querychat_app.R	Main implementation of the new querychat_app() function with complete Shiny UI/server logic
pkg-r/R/querychat_tools.R	New tool system with tool_update_dashboard() and tool_query() functions
pkg-r/R/querychat.R	Refactored to use new tool system and added JavaScript dependency management
pkg-r/inst/htmldep/querychat.js	JavaScript for handling dashboard update button interactions
pkg-r/man/querychat_app.Rd	Documentation for the new function
pkg-r/pkgdown/_pkgdown.yml	Added new function to package documentation index
pkg-r/NAMESPACE	Exported the new querychat_app() function
pkg-r/DESCRIPTION	Updated dependencies for new functionality
pkg-r/NEWS.md	Documented the new feature

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