fix: Expose id in ui/server methods to support Shiny for R modules and multiple instances

[cpsievert]

Closes #169

This PR introduces proper support for using QueryChat within Shiny (for R) modules by allowing explicit id parameter overrides in $ui(), $sidebar(), and $server() methods.

Key Changes

1. Added id parameter to $ui(), $sidebar(), and $server() methods:

• Users can now explicitly pass an id when calling these methods
• When not provided, falls back to the ID specified at initialization
• In Shiny modules, users pass namespaced IDs using standard Shiny module patterns: id = ns("your_id")

2. Follows idiomatic Shiny module patterns:

• Uses the standard Shiny approach where module IDs are wrapped in ns() in the UI function
• The corresponding server function receives the unwrapped ID
• This is the established pattern that Shiny developers are familiar with

3. Enables multiple instances from the same QueryChat object:

• By allowing explicit id override, users can create multiple chat interfaces from a single QueryChat instance
• Useful for both module and non-module scenarios where multiple chats are needed

Implementation Details

• Modified $ui() and $sidebar() to accept an optional id parameter instead of ns function
• Modified $server() to accept an optional id parameter
• When id is not provided, falls back to self$id with automatic namespace detection (via namespaced_id()) for UI methods
• Updated documentation to clarify the new module usage pattern
• Removed the error check that prevented setting id directly

Usage

In a Shiny module UI function:

module_ui <- function(id, qc) {
  ns <- NS(id)
  card(qc$ui(id = ns("qc-ui")))  # Standard Shiny module pattern
}

In a Shiny module server function:

module_server <- function(id, qc) {
  moduleServer(id, function(input, output, session) {
    qc$server(id = "qc-ui")  # Matches the unwrapped ID from UI
  })
}

In a regular Shiny app (no module):

ui <- page_fluid(
  qc$ui()  # Uses default ID from initialization
)

server <- function(input, output, session) {
  qc$server()  # Uses default ID from initialization
}

[gadenbuie]

I liked considering the idea of passing in ns() (it's a creative solution!), but it feels little off compared to the established patterns we use with Shiny modules.

In #173 I'm proposing that we expose id directly, while still allowing for the server-side rendered case to "just work". More than just solving the Shiny modules use case, that opens up re-using a qc object for more than chat instance.

[cpsievert]

@gadenbuie mind updating the description and taking this over the finish line?

[gadenbuie]

@cpsievert I updated the PR description, made the "querychat_" + table_name for default ID, and added an example app in the R package as 03-module-app. I also made similar changes on the Python side (except for adding an example app).

[cpsievert]

Thanks! LGTM other than the one suggestion.