Use calendar-aligned axes on every date chart #185

Problem

#183 put the Cash Balance Trend chart on calendar-aligned date labels, but the other date charts still use evenly spaced or arbitrary dates. The per-account trend charts on Analytics show labels like Nov 3, May 10, Oct 30, Apr 13, Oct 28 in All, and their 1M/1Y views start at the first transaction in the period instead of the 1st. Their past-month and past-year balances are also computed from the current balance without the movements after the period, so they are offset. The portfolio history, investment detail, manual valuation and AI cash outlook charts have the same kind of axis.

When months and years appear together on an axis (for example 2025, Apr, Jul, Oct, 2026), the year labels look the same as the month labels, so the year boundary is hard to spot.

Steps to reproduce

1. Open Analytics with more than a year of history and choose All.
2. Look at the per-account trend charts' x-axis labels.
3. Choose 1M or a past month and compare where each account chart starts and its balances.

Expected behavior

Every date-axis chart labels calendar boundaries (days, months, quarters or years) that fit its width. Per-account 1M and 1Y charts start on the period's first day with the carried balance, like Cash Balance Trend, and show correct balances for past periods. Year labels are emphasized when they appear among month labels.

Acceptance criteria

• Per-account trends, portfolio history, the investment detail chart, manual valuations and AI cash outlook use calendar-aligned ticks on desktop and mobile.
• Per-account 1M/1Y charts start on the 1st with the carried balance and reconstruct past periods from the full ledger.
• Year labels among month labels are visually emphasized in both themes.
• Tests cover the year emphasis and per-account clipping.

Context or visuals

Follow-up to #183 (PR #184).