fix: Transfers were not syncing between accounts (#987)

* fix: Include investment_contribution in transfer? check and protect transfer entries from sync

Transfer transactions with kind "investment_contribution" were not recognized
as transfers by the UI, causing missing +/- indicators, "Transfer" labels,
and showing regular transaction forms instead of transfer details.

Also adds user_modified: true to entries created via TransferMatchesController
and SetAsTransferOrPayment rule action to protect them from provider sync
overwrites, matching the existing behavior in Transfer::Creator.

https://claude.ai/code/session_019BZ5Z1aqKSK3cRdR81P5Jg

* fix: Centralize transfer/budget kind constants for consistent investment_contribution handling

Define TRANSFER_KINDS and BUDGET_EXCLUDED_KINDS on Transaction to eliminate
hard-coded kind lists scattered across filters, rules, and analytics code.

investment_contribution is now consistently treated as a transfer in search
filters, rule conditions, and UI display (via TRANSFER_KINDS), while budget
analytics correctly continue treating it as an expense (via BUDGET_EXCLUDED_KINDS).

https://claude.ai/code/session_019BZ5Z1aqKSK3cRdR81P5Jg

* fix: Update tests for consistent investment_contribution as transfer kind

- search_test: loan_payment is now in TRANSFER_KINDS, so uncategorized
  filter correctly excludes it (same as funds_movement/cc_payment)
- condition_test: investment_contribution is now a transfer kind, so it
  matches the transfer filter rather than expense filter

https://claude.ai/code/session_019BZ5Z1aqKSK3cRdR81P5Jg

* fix: Eliminate SQL injection warnings in Transaction::Search

Replace string-interpolated SQL with parameterized queries:
- totals: use sanitize_sql_array with ? placeholders
- apply_category_filter: pass TRANSFER_KINDS as bind parameter
- apply_type_filter: use where(kind:)/where.not(kind:) and
  parameterized IN (?) for compound OR conditions
- Remove unused transfer_kinds_sql helper

https://claude.ai/code/session_019BZ5Z1aqKSK3cRdR81P5Jg

---------

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

app/models/rule/action_executor/set_as_transfer_or_payment.rb

@@ -46,6 +46,7 @@ class Rule::ActionExecutor::SetAsTransferOrPayment < Rule::ActionExecutor
           currency: entry.currency,
           date: entry.date,
           name: "#{target_account.liability? ? "Payment" : "Transfer"} #{entry.amount.negative? ? "to #{target_account.name}" : "from #{entry.account.name}"}",
+          user_modified: true,
         )
       )