Feat: /import endpoint & drag-n-drop imports (#501)

* Implement API v1 Imports controller

- Add Api::V1::ImportsController with index, show, and create actions
- Add Jbuilder views for index and show
- Add integration tests
- Implement row generation logic in create action
- Update routes

* Validate import account belongs to family

- Add validation to Import model to ensure account belongs to the same family
- Add regression test case in Api::V1::ImportsControllerTest

* updating docs to be more detailed

* Rescue StandardError instead of bare rescue in ImportsController

* Optimize Imports API and fix documentation

- Implement rows_count counter cache for Imports
- Preload rows in Api::V1::ImportsController#show
- Update documentation to show correct OAuth scopes

* Fix formatting in ImportsControllerTest

* Permit all import parameters and fix unknown attribute error

* Restore API routes for auth, chats, and messages

* removing pr summary

* Fix trailing whitespace and configured? test failure

- Update Import#configured? to use rows_count for performance and consistency
- Mock rows_count in TransactionImportTest
- Fix trailing whitespace in migration

* Harden security and fix mass assignment in ImportsController

- Handle type and account_id explicitly in create action
- Rename import_params to import_config_params for clarity
- Validate type against Import::TYPES

* Fix MintImport rows_count update and migration whitespace

- Update MintImport#generate_rows_from_csv to update rows_count counter cache
- Fix trailing whitespace and final newline in AddRowsCountToImports migration

* Implement full-screen Drag and Drop CSV import on Transactions page

- Add DragAndDropImport Stimulus controller listening on document
- Add full-screen overlay with icon and text to Transactions index
- Update ImportsController to handle direct file uploads via create action
- Add system test for drag and drop functionality

* Implement Drag and Drop CSV upload on Import Upload page

- Add drag-and-drop-import controller to import/uploads/show
- Add full-screen overlay to import/uploads/show
- Annotate upload form and input with drag-and-drop targets
- Add PR_SUMMARY.md

* removing pr summary

* Add file validation to ImportsController

- Validate file size (max 10MB) and MIME type in create action
- Prevent memory exhaustion and invalid file processing
- Defined MAX_CSV_SIZE and ALLOWED_MIME_TYPES in Import model

* Refactor dragLeave logic with counter pattern to prevent flickering

* Extract shared drag-and-drop overlay partial

- Create app/views/imports/_drag_drop_overlay.html.erb
- Update transactions/index and import/uploads/show to use the partial
- Reduce code duplication in views

* Update Brakeman and harden ImportsController security

- Update brakeman to 7.1.2
- Explicitly handle type assignment in ImportsController#create to avoid mass assignment
- Remove :type from permitted import parameters

* Fix trailing whitespace in DragAndDropImportTest

* Don't commit LLM comments as file

* FIX add api validation

---------

Co-authored-by: Carlos Adames <cj@Carloss-MacBook-Air.local>
Co-authored-by: Juan José Mata <jjmata@jjmata.com>
Co-authored-by: sokie <sokysrm@gmail.com>

app/views/api/v1/imports/index.json.jbuilder

@@ -0,0 +1,21 @@
+json.data do
+  json.array! @imports do |import|
+    json.id import.id
+    json.type import.type
+    json.status import.status
+    json.created_at import.created_at
+    json.updated_at import.updated_at
+    json.account_id import.account_id
+    json.rows_count import.rows_count
+    json.error import.error if import.error.present?
+  end
+end
+
+json.meta do
+  json.current_page @pagy.page
+  json.next_page @pagy.next
+  json.prev_page @pagy.prev
+  json.total_pages @pagy.pages
+  json.total_count @pagy.count
+  json.per_page @per_page
+end

app/views/api/v1/imports/show.json.jbuilder

@@ -0,0 +1,30 @@
+json.data do
+  json.id @import.id
+  json.type @import.type
+  json.status @import.status
+  json.created_at @import.created_at
+  json.updated_at @import.updated_at
+  json.account_id @import.account_id
+  json.error @import.error if @import.error.present?
+
+  json.configuration do
+    json.date_col_label @import.date_col_label
+    json.amount_col_label @import.amount_col_label
+    json.name_col_label @import.name_col_label
+    json.category_col_label @import.category_col_label
+    json.tags_col_label @import.tags_col_label
+    json.notes_col_label @import.notes_col_label
+    json.account_col_label @import.account_col_label
+    json.date_format @import.date_format
+    json.number_format @import.number_format
+    json.signage_convention @import.signage_convention
+  end
+
+  json.stats do
+    json.rows_count @import.rows_count
+    json.valid_rows_count @import.rows.select(&:valid?).count if @import.rows.loaded?
+  end
+
+  # Only show a subset of rows for preview if needed, or link to a separate rows endpoint
+  # json.sample_rows @import.rows.limit(5)
+end