Add missing edit view and Edit link for logs (#1871)

LogsController#edit/#update, the route, and the shared _form partial
already existed, but app/views/logs/edit.html.slim was never added, so
visiting the edit URL crashed with a missing-template error. The show
page also had no Edit link, so there was no way to reach the page at
all. Add the template (mirrors new.html.slim) and an Edit button next
to Delete on the show page.

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: Yanchek99

app/views/logs/edit.html.slim

@@ -0,0 +1,2 @@
+.container
+  = render 'form', log: @log

app/views/logs/show.html.slim

@@ -8,5 +8,6 @@
         - @log.movement_logs.each do |ml|
           .col-12
             span = measurable_message(ml)
-      .mt-2.d-grid
+      .mt-2.d-grid.gap-2
+        = link_to 'Edit', edit_workout_log_path(@log.workout, @log), class: 'btn btn-primary'
         = link_to 'Delete', log_path(@log), data: { turbo_method: :delete }, class: 'btn btn-danger'