Add return breakdown dialog with PnL history chart

[dbigham]

Summary

• compute trailing return metrics and P&L history on the server and expose them in the funding summary payload
• surface the new return data in the client, including sanitization, and wire the annualized return metric to open a detailed dialog
• introduce a return breakdown dialog with time period controls, CAD/% toggle, and styled chart matching existing visuals

Testing

• npm run lint

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https://chatgpt.com/codex/tasks/task_e_68e279c70b10832d81a0e98a22887154

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Aggregated cash flows mis-handle per-account final equity entries

The all‑accounts summary feeds every account’s cashFlowsCad directly into buildFundingPerformanceSummary. Those per‑account arrays already contain a final positive entry representing that account’s current equity. When concatenated, all but one of those positive entries land in the “contributions” slice inside buildFundingPerformanceSummary, where they are negated and treated as withdrawals. As soon as more than one account is selected, the resulting net‑deposit totals and PnL history become incorrect (final equity for account A is subtracted from the aggregate deposits). The aggregate cash flows should either strip per‑account terminal entries and add one combined terminal balance, or the builder should ignore positive entries before the final one; otherwise the rendered return chart and trailing return numbers for “All accounts” are wrong.

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