Let an entrypoint's description be edited in place (closes #392)

An entrypoint's description was set when it was added and could never change, so renaming one meant deleting it and adding a new one with a new URL every sender had to be given again. Each entrypoint on the webhook page now has an Edit button, in the shared secondary style, that opens its description in place with Save and Cancel and keeps its URL. The save goes through the same login, CSRF and ownership checks as the other entrypoint actions; an empty description shows as "Entrypoint". Activate and deactivate now write only the active column, so they cannot undo an edit. Tests cover each, through the router and the browser.

Model: opus-5-5

templates/source_detail.html

@@ -54,15 +54,29 @@
 
             <div class="divide-y divide-gray-100">
                 {{range .Entrypoints}}
-                <div class="p-4">
+                <div class="p-4" x-data="collapsible">
                     <div class="flex flex-wrap items-center justify-between gap-2 mb-1">
-                        <span class="text-sm font-medium text-gray-900">{{if .Description}}{{.Description}}{{else}}Entrypoint{{end}}</span>
+                        <span x-show="closed" class="text-sm font-medium text-gray-900">{{if .Description}}{{.Description}}{{else}}Entrypoint{{end}}</span>
+                        <!-- Edit shows this form in place of the
+                             description and hides until it closes, and
+                             Cancel resets what was typed. With
+                             autocomplete="off", going back to the page
+                             does not put unsaved text back either, so
+                             the form always opens on the saved
+                             description. -->
+                        <form x-show="open" x-cloak method="POST" action="/hook/{{$.Webhook.ID}}/entrypoints/{{.ID}}/edit" class="flex w-full gap-2">
+                            <input type="hidden" name="csrf_token" value="{{$.CSRFToken}}">
+                            <input type="text" name="description" value="{{.Description}}" autocomplete="off" placeholder="Description (optional)" class="input text-sm flex-1">
+                            <button type="submit" class="btn-primary text-sm">Save</button>
+                            <button type="reset" @click="toggle" class="btn-secondary text-sm">Cancel</button>
+                        </form>
                         <div class="flex flex-wrap items-center gap-2">
                             {{if .Active}}
                             <span class="badge-success">Active</span>
                             {{else}}
                             <span class="badge-error">Inactive</span>
                             {{end}}
+                            <button type="button" x-show="closed" @click="toggle" class="btn-small" title="Edit">Edit</button>
                             <form method="POST" action="/hook/{{$.Webhook.ID}}/entrypoints/{{.ID}}/toggle" class="inline">
                                 <input type="hidden" name="csrf_token" value="{{$.CSRFToken}}">
                                 <button type="submit" class="btn-small" title="{{if .Active}}Deactivate{{else}}Activate{{end}}">