Providers factory (#250)

* Implement providers factory

* Multiple providers sync support

- Proper Multi-Provider Syncing: When you click sync on an account with multiple providers (e.g., both Plaid and SimpleFin), all provider items are synced
- Better API: The existing account.providers method already returns all providers, and account.provider returns the first one for backward compatibility
- Correct Holdings Deletion Logic: Holdings can only be deleted if ALL providers allow it, preventing accidental deletions that would be recreated on next sync
TODO: validate this is the way we want to go? We would need to check holdings belong to which account, and then check provider allows deletion. More complex
- Database Constraints: The existing validations ensure an account can have at most one provider of each type (one PlaidAccount, one SimplefinAccount, etc.)

* Add generic provider_import_adapter

* Finish unified import strategy

* Update app/models/plaid_account.rb

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Signed-off-by: soky srm <sokysrm@gmail.com>

* Update app/models/provider/factory.rb

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Signed-off-by: soky srm <sokysrm@gmail.com>

* Fix account linked by plaid_id instead of external_id

* Parse numerics to BigDecimal

Parse numerics to BigDecimal before computing amount; guard nils.

Avoid String * String and float drift; also normalize date.

* Fix incorrect usage of assert_raises.

* Fix linter

* Fix processor test.

* Update current_balance_manager.rb

* Test fixes

* Fix plaid linked account test

* Add support for holding per account_provider

* Fix proper account access

Also fix account deletion for simpefin too

* FIX match tests for consistency

* Some more factory updates

* Fix account schema for multipe providers

  Can do:
  - Account #1 → PlaidAccount + SimplefinAccount (multiple different providers)
  - Account #2 → PlaidAccount only
  - Account #3 → SimplefinAccount only

  Cannot do:
  - Account #1 → PlaidAccount + PlaidAccount (duplicate provider type)
  - PlaidAccount #123 → Account #1 + Account #2 (provider linked to multiple accounts)

* Fix account setup

- An account CAN have multiple providers (the schema shows account_providers with unique index on [account_id, provider_type])
  - Each provider should maintain its own separate entries
  - We should NOT update one provider's entry when another provider syncs

* Fix linter and guard migration

* FIX linter issues.

* Fixes

- Remove duplicated index
- Pass account_provider_id
- Guard holdings call to avoid NoMethodError

* Update schema and provider import fix

* Plaid doesn't allow holdings deletion

* Use ClimateControl for proper env setup

* No need for this in .git

---------

Signed-off-by: soky srm <sokysrm@gmail.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Juan José Mata <juanjo.mata@gmail.com>

app/models/account/linkable.rb

@@ -2,13 +2,17 @@ module Account::Linkable
   extend ActiveSupport::Concern
 
   included do
+    # New generic provider association
+    has_many :account_providers, dependent: :destroy
+
+    # Legacy provider associations - kept for backward compatibility during migration
     belongs_to :plaid_account, optional: true
     belongs_to :simplefin_account, optional: true
   end
 
   # A "linked" account gets transaction and balance data from a third party like Plaid or SimpleFin
   def linked?
-    plaid_account_id.present? || simplefin_account_id.present?
+    account_providers.any?
   end
 
   # An "offline" or "unlinked" account is one where the user tracks values and
@@ -17,4 +21,42 @@ module Account::Linkable
     !linked?
   end
   alias_method :manual?, :unlinked?
+
+  # Returns the primary provider adapter for this account
+  # If multiple providers exist, returns the first one
+  def provider
+    return nil unless linked?
+
+    @provider ||= account_providers.first&.adapter
+  end
+
+  # Returns all provider adapters for this account
+  def providers
+    @providers ||= account_providers.map(&:adapter).compact
+  end
+
+  # Returns the provider adapter for a specific provider type
+  def provider_for(provider_type)
+    account_provider = account_providers.find_by(provider_type: provider_type)
+    account_provider&.adapter
+  end
+
+  # Convenience method to get the provider name
+  def provider_name
+    provider&.provider_name
+  end
+
+  # Check if account is linked to a specific provider
+  def linked_to?(provider_type)
+    account_providers.exists?(provider_type: provider_type)
+  end
+
+  # Check if holdings can be deleted
+  # If account has multiple providers, returns true only if ALL providers allow deletion
+  # This prevents deleting holdings that would be recreated on next sync
+  def can_delete_holdings?
+    return true if unlinked?
+
+    providers.all?(&:can_delete_holdings?)
+  end
 end