CLI Pulse Desktop v0.10.2

Compare mode — a new Compare to previous period toggle (Settings → Date range) adds a compact ▲/▼ N% vs-previous badge to the window figures on Overview (cost tile + provider bars) and Providers (per-provider cost & I/O tokens). It compares the current N-day window against the equal-length window immediately before it (offered for ranges ≤ 90 days). Closes the last deferred v0.10.0 item.

Window math is a pure, unit-tested, timezone-safe module; a dedicated 180-day baseline scan (its own cache namespace) gives a correct previous period without disturbing the main scan. No backend change.

See the CHANGELOG for details.