fix: Preserve tags on bulk edits (take 3) (#889)

* fix: handle tags separately from entryable_attributes in bulk updates

Tags use a join table (taggings) rather than a direct column, which means
empty tag_ids clears all tags rather than meaning "no change". This caused
bulk category-only edits to accidentally clear existing tags.

This fix:
- Removes tag_ids from entryable_attributes in Entry.bulk_update!
- Adds update_tags parameter to explicitly control tag updates
- Uses params.key?(:tag_ids) in controller to detect explicit tag changes
- Preserves existing tags when tag_ids is not provided in the request

This is a cleaner architectural solution compared to tracking "touched"
state in the frontend, as it properly acknowledges the semantic difference
between column attributes and join table associations.

https://claude.ai/code/session_014CsmTwjteP4qJs6YZqCKnY

* fix: handle tags separately in API transaction updates

Apply the same pattern to the API endpoint: tags are now handled
separately from entryable_attributes to distinguish between "not
provided" (preserve existing tags) and "explicitly set to empty"
(clear all tags).

This allows API consumers to:
- Update other fields without affecting tags (omit tag_ids)
- Clear all tags (send tag_ids: [])
- Set specific tags (send tag_ids: [id1, id2])

https://claude.ai/code/session_014CsmTwjteP4qJs6YZqCKnY

* Proposed fix

* fix: improve tag handling in bulk updates for transactions

* fix: allow bulk edit to clear/preserve tags by omitting hidden multi-select field

* PR comments

* Dumb copy/paste error

* Linter

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Juan José Mata <juanjo.mata@gmail.com>
Co-authored-by: Juan José Mata <jjmata@jjmata.com>

app/views/transactions/bulk_updates/new.html.erb

@@ -12,7 +12,7 @@
           <div class="space-y-2">
             <%= form.collection_select :category_id, Current.family.categories.alphabetically, :id, :name, { prompt: "Select a category", label: "Category", class: "text-subdued" } %>
             <%= form.collection_select :merchant_id, Current.family.available_merchants.alphabetically, :id, :name, { prompt: "Select a merchant", label: "Merchant", class: "text-subdued" } %>
-            <%= form.select :tag_ids, Current.family.tags.alphabetically.pluck(:name, :id), { include_blank: "None", multiple: true, label: "Tags" } %>
+            <%= form.select :tag_ids, Current.family.tags.alphabetically.pluck(:name, :id), { include_blank: "None", multiple: true, label: "Tags", include_hidden: false } %>
             <%= form.text_area :notes, label: "Notes", placeholder: "Enter a note that will be applied to selected transactions", rows: 5 %>
           </div>
         <% end %>