feat: in-app delete for journal trades + account purge

[ghwmelite-dotcom]

Summary

Adds proper in-app delete controls so cleaning up data (e.g. old synced trades after re-syncing an account) never requires raw production SQL again. Every path is ownership-scoped — a user can only ever delete their own rows.

Journal deletes

• DELETE /journal/trades/:accountId — filter-aware bulk delete (same from/to/symbol/direction/session_tag filters as the GET list); no filters = clear the account's whole journal. Returns the deleted count.
• DELETE /journal/trades/:accountId/:dealTicket — delete one trade.
• JournalPage: a Delete button opens a modal with two modes — Before a date (pick e.g. 2026-06-01 to remove everything before June 2026; UTC) and Clear entire journal (type the account name to confirm) — plus a per-row trash button.

Account hard-delete (purge)

• DELETE /accounts/:id/purge — atomic db.batch() that removes the account and every row referencing it: journal_trades, symbol_mappings, follower_config, prop_rules, daily_stats, blocked_trades, firm_templates, signals, executions, provider_profiles, marketplace_subscriptions, then the account itself. Distinct from the existing soft deactivate (DELETE /accounts/:id).
• Delete Account modal gains a gated "permanently erase this account and all its data" path (type the account name to confirm).

Stores gain deleteTrades/deleteTrade (journal) and purgeAccount (accounts).

Safety

• All endpoints reuse the existing ownership check (verifyAccountOwnership / WHERE user_id = ?) — multi-tenant safe.
• Destructive UI actions require explicit confirmation; full-journal-clear and account-purge require typing the account name.
• Purge is a single atomic batch: if any statement fails, nothing is deleted.

Verification

• Table/column names for the purge were taken directly from the migrations (0001, 0004, 0006, 0008, 0012).
• tsc/vite build can't run in the dev environment (no node_modules) — CI Typecheck gates the deploy. I have not exercised the delete flows against a live DB.

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