feat: default history views to a 7-day window - #13

The Profiles HISTORY panel and the menu-bar popover were showing changes from over a month ago. Root cause: the 90-day retention in record_at only prunes on write, so an install that hasn't changed an association in weeks never prunes at all.

Fixes it by applying the window on read (history::recent_within), and makes the window a user-facing preference.

Behavior

• Default lookback is 7 days on all three surfaces: Profiles HISTORY, the popover's Recent Changes, and openwith history.
• Settings → Behavior → "Show history for": 1 week / 1 month / All (persisted as historyWindowDays, shared by both windows).
• CLI: openwith history --days N and --all.

Nothing is deleted

This is a display window, not a retention change:

• The ledger keeps its existing 90-day / 500-event cap.
• The HISTORY panel head shows the active window plus a session-only Show all toggle.
• undo_change and openwith undo still read the unwindowed ledger, so an event hidden by the window stays revertible.

A "3 months" segment was considered and dropped — the ledger's own 90-day cap makes it indistinguishable from "All".

Verification

Exercised against a running app, not just a compile:

• Profiles panel shows Last 7 days with the correct empty state; Show all round-trips the hidden rows and flips the head label.
• Popover reads Nothing in the last 7 days.; its storage listener now refetches rather than only re-rendering, so widening in the main window pulls the extra rows.
• Settings row renders on one line with 1 week active.
• CLI: default windowed, --all shows all 24 retained events, --days 60 shows 3, --all --days 3 correctly rejected.

cargo fmt --check, cargo clippy --all-targets --all-features -- -D warnings, cargo test (25, +2 new), and npm run build all clean.

Full GUI smoke-test checklist against a built bundle still pending — see the release notes below.