feat: Toasts (#1246)

* feat: Add toast notification R API

Implement core R functions for toast notifications:
- toast(): Create toast objects with customizable options
- show_toast(): Display toasts in Shiny apps
- hide_toast(): Manually dismiss toasts
- toast_header(): Create structured headers with icons/status

---------

Co-authored-by: Carson Sievert <[email protected]>

Author: gadenbuie

.Rbuildignore

@@ -35,3 +35,5 @@ inst/lib/bsw3/.npmignore
 ^AGENTS\.md$
 ^[.]?air[.]toml$
 ^\.vscode$
+^inst/examples-shiny/toast/\.gitignore$
+^inst/examples-shiny/brand\.yml/\.gitignore$

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: bslib
 Title: Custom 'Bootstrap' 'Sass' Themes for 'shiny' and 'rmarkdown'
-Version: 0.9.0.9000
+Version: 0.9.0.9002
 Authors@R: c(
     person("Carson", "Sievert", , "[email protected]", role = c("aut", "cre"),
            comment = c(ORCID = "0000-0002-4958-2844")),
@@ -115,6 +115,7 @@ Collate:
     'shiny-devmode.R'
     'sidebar.R'
     'staticimports.R'
+    'toast.R'
     'tooltip.R'
     'utils-deps.R'
     'utils-shiny.R'

NAMESPACE

@@ -1,6 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
 S3method(as.tags,bslib_sidebar)
+S3method(as.tags,bslib_toast)
 S3method(bind_task_button,ExtendedTask)
 S3method(bind_task_button,default)
 S3method(brand_resolve,"NULL")
@@ -17,9 +18,14 @@ S3method(print,bslib_fragment)
 S3method(print,bslib_navbar_options)
 S3method(print,bslib_page)
 S3method(print,bslib_showcase_layout)
+S3method(print,bslib_toast)
 S3method(print,bslib_value_box_theme)
 S3method(save_html,bslib_fragment)
 S3method(save_html,bslib_page)
+S3method(toast_component_header,bslib_toast_header)
+S3method(toast_component_header,character)
+S3method(toast_component_header,default)
+S3method(toast_component_header,list)
 export(accordion)
 export(accordion_panel)
 export(accordion_panel_close)
@@ -86,6 +92,7 @@ export(font_collection)
 export(font_face)
 export(font_google)
 export(font_link)
+export(hide_toast)
 export(input_dark_mode)
 export(input_submit_textarea)
 export(input_switch)
@@ -140,13 +147,16 @@ export(popover)
 export(precompiled_css_path)
 export(remove_all_fill)
 export(run_with_themer)
+export(show_toast)
 export(showcase_bottom)
 export(showcase_left_center)
 export(showcase_top_right)
 export(sidebar)
 export(sidebar_toggle)
 export(theme_bootswatch)
 export(theme_version)
+export(toast)
+export(toast_header)
 export(toggle_dark_mode)
 export(toggle_popover)
 export(toggle_sidebar)