Improve investment activity labels UX and add convert-to-trade feature (#649)

* Add `investment_activity_label` to trades and enhance activity label handling

- Introduced `investment_activity_label` column to the `trades` table with a migration.
- Backfilled existing `trades` with activity labels based on quantity (`Buy`, `Sell`, or `Other`).
- Replaced `category_id` in trades with `investment_activity_label` for better alignment with transaction labels.
- Updated views and controllers to display and manage activity labels for trades.
- Added localized badge components for displaying and editing labels dynamically.
- Enhanced `PlaidAccount::Investments::TransactionsProcessor` to assign and process activity labels automatically.
- Added investment flows section to reports for tracking contributions and withdrawals.
- Refactored related tests and models for consistency and to ensure proper validation and filtering.

* Improve handling of `investment_activity_label`, trade type, and security selection in trades and transactions

- Refined label assignment logic in `trades_controller` to default to `Buy`/`Sell` based on transaction nature.
- Simplified security selection in `transactions_controller` by resolving via unique IDs or custom tickers.
- Streamlined UI for trade and transaction forms by updating dropdown options and label text.
- Enabled quick-edit badges to open `convert_to_trade` modal when applicable, enhancing flexibility.
- Adjusted tests and views to align with updated workflows and ensure consistent behavior.

* Improve handling of `investment_activity_label`, trade type, and security selection in trades and transactions

- Refined label assignment logic in `trades_controller` to default to `Buy`/`Sell` based on transaction nature.
- Simplified security selection in `transactions_controller` by resolving via unique IDs or custom tickers.
- Streamlined UI for trade and transaction forms by updating dropdown options and label text.
- Enabled quick-edit badges to open `convert_to_trade` modal when applicable, enhancing flexibility.
- Adjusted tests and views to align with updated workflows and ensure consistent behavior.

* Improve handling of `investment_activity_label`, trade type, and security selection in trades and transactions

- Refined label assignment logic in `trades_controller` to default to `Buy`/`Sell` based on transaction nature.
- Simplified security selection in `transactions_controller` by resolving via unique IDs or custom tickers.
- Streamlined UI for trade and transaction forms by updating dropdown options and label text.
- Enabled quick-edit badges to open `convert_to_trade` modal when applicable, enhancing flexibility.
- Adjusted tests and views to align with updated workflows and ensure consistent behavior.

* Add safeguard for `dropdownTarget` existence in quick edit controller

- Prevent errors by ensuring `dropdownTarget` is present before toggling its visibility.

* Fix undefined method 'category' for Trade on mobile view

Trade model uses investment_activity_label, not category. The upstream
merge introduced a call to trade.category which doesn't exist. Use the
activity label badge on mobile instead.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Fix activity label logic for zero/blank quantity and sell inference

- Return `nil` for blank or zero quantity in `investment_activity_label_for`.
- Correct `is_sell` logic to use the amount’s sign properly in `transactions_controller`.

* Fix i18n key paths in transactions controller for convert_to_trade

- Update flash message translations to use full i18n paths.
- Use `BigDecimal` for quantity and price calculations to improve precision.

---------

Co-authored-by: Josh Waldrep <joshua.waldrep5+github@gmail.com>
Co-authored-by: luckyPipewrench <luckypipewrench@proton.me>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

test/support/entries_test_helper.rb

@@ -41,7 +41,8 @@ module EntriesTestHelper
       qty: qty,
       security: security,
       price: trade_price,
-      currency: currency
+      currency: currency,
+      investment_activity_label: qty > 0 ? "Buy" : "Sell"
 
     account.entries.create! \
       name: "Trade",

test/support/ledger_testing_helper.rb

@@ -77,7 +77,8 @@ module LedgerTestingHelper
           qty: entry_data[:qty],
           security: security,
           price: entry_data[:price],
-          currency: currency
+          currency: currency,
+          investment_activity_label: entry_data[:qty] > 0 ? "Buy" : "Sell"
         )
 
         created_account.entries.create!(