add aggregated dashboard mode and account switcher

[rx18-eng]

Adds an aggregated dashboard mode: a toggle that lets the main account view combined stats across every sub-account on Home, Workers, Payouts, and Generated BTC, plus a sidebar switcher to drill into one sub-account directly.

Also fixes the Workers and Payouts mobile views, which were never actually building a mobile card layout despite the design calling for one (the same gap I'd just caught while doing Generated BTC).

Verification

• typecheck, lint, and build all clean.
• 225 tests passing.
• Tested with a real staging login and real sub-accounts.
• Verified desktop and mobile in both aggregated and single-account modes.
• No console errors.

Also caught and fixed two bugs while testing the full flow:

• Switching into a sub-account while aggregated mode was on used to leave the account switcher with no way back (that endpoint returns empty once authenticated as the sub-account).
• Worker rows across sub-accounts were keyed by sub-account name instead of ID, so two same-named sub-accounts would've collided in the table and CSV export.

Not in this PR

• Generated BTC's Mode/Estimated Payout columns and an Average Uptime card (not backed by the API).
• The full 16-column financial report from the improvements doc (most columns are unbacked).
• Watcher Links aggregation (checked live; that page already lists every account regardless of the toggle).

[Priceless-P]

• Don't show sub account nav item for a subaccount.
• After switching, if the user previously in sub account page or any other restricted page and switches, it should redirect to home
• Error in generated btc page in aggregated view, please check
• Subaccounts should not be able to change btc address, update password or reset 2fa
• Aggregated mode can get stuck when there are no subaccounts because the exit button disappears. Only turn it on when subaccounts actually exist.
• The aggregated Workers page excludes the main account’s workers. It should combine workers from the main account and all subaccounts.
• In aggregated mode, the home page mining charts still shows only the main account hashrate