Display item actions on show view

[Flo0807]

depends on #1688

[Copilot]

Pull request overview

This PR enables item actions to be displayed on the show view, allowing users to perform actions on individual items from the detail page. The implementation refactors existing item action logic into shared functions to maintain consistency between index and show views.

• Adds item action support to the show view with modal confirmation support
• Extracts common item action handling logic into reusable Backpex.ItemAction functions
• Creates a new Backpex.HTML.ItemAction component for the action confirmation modal

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
lib/backpex/live_resource/show.ex	Adds item action handling to show view including action assignment, event handlers, and navigation logic
lib/backpex/live_resource/index.ex	Refactors to use shared item action functions from Backpex.ItemAction module
lib/backpex/item_actions/item_action.ex	Adds shared handle_item_action and assign_action_changeset functions for reuse across views
lib/backpex/live_components/form_component.ex	Renames handle_item_action to handle_form_item_action to avoid naming conflicts and changes navigation method
lib/backpex/html/item_action.ex	New component module providing the reusable action confirmation modal
lib/backpex/html/resource/resource_show.html.heex	Includes the action confirmation modal in the show view template
lib/backpex/html/resource/resource_index_table.html.heex	Updates to use the new filter_item_actions function for consistency
lib/backpex/html/resource/resource_index.html.heex	Extracts action modal into reusable component
lib/backpex/html/resource.ex	Refactors item action filtering into a single public filter_item_actions function and updates visibility check to public action_visible?
lib/backpex/live_resource.ex	Updates show page title template to render item actions as buttons
guides/actions/item-actions.md	Documents the new :show placement option and fixes grammar
demo/lib/demo_web/live/tag_live.ex	Adds :show to duplicate action visibility configuration as a demo

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[pehbehbeh]

After using the edit action I would have expected to return to the show view after "save" (and especially after "go back"). Could we maybe add that via the return_to functionality?

[Flo0807]

After using the edit action I would have expected to return to the show view after "save" (and especially after "go back"). Could we maybe add that via the return_to functionality?

This is also broken on develop. I fixed it here #1688

(I've added some tests for item actions in this PR to make sure they work and redirect as expected)

[Flo0807]

I've added a bunch of additional tests.

[pehbehbeh]

👍 👍 👍