feat: add gasoline ICE cost comparison from user assumptions

CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- **Gasoline comparison** — in Settings, add an equivalent gasoline car's fuel economy (L/100 km or mpg) and pump price (per liter or per gallon). Cost Analytics then shows a neutral "vs gasoline" card comparing your Tesla charging cost for the selected range against what the same distance would have cost in gasoline, including the estimated volume used and the difference in absolute terms and percent. Distances from TeslaMate are never converted; only the ICE assumptions are converted when their unit doesn't match the length unit already in use.
+- **Utility-rate cost estimates** — set your home (AC) rate and, optionally, a DC/public rate per kWh in Settings. When TeslaMate has no price for a charging session, MateDroid now fills in the gap with your local rate so cost analytics and trip summaries stay useful. Recorded TeslaMate prices are always preferred (including free sessions); estimates are labelled honestly and never overwrite what was recorded. DC sessions use the DC rate when set, and fall back to the home rate otherwise so a single rate still works.
+- **Cost analytics screen** — a new "Costs" entry on the dashboard opens a focused view of your charging spend. Pick 7/30/90-day or all-time windows to see known cost, cost per 100 km/mi (only when every charge in range is priced), average cost per kWh, energy added, and a coverage summary that surfaces missing prices and free sessions honestly.
+- **Cost summary home-screen widget** — a read-only Glance widget that mirrors the Cost Analytics numbers on your home screen. Configurable per car with 7/30/90-day ranges, refreshes on each background sync, and never contacts the car or the API (all values come from the Room cache).
+- **Richer Trips summary** — the Trips list summary now includes energy used, average efficiency, energy charged, charging cost, and cost per 100 km/mi. Known costs stay visible when only some sessions are priced, with an honest coverage note; cost/100 only appears when every charge in range is priced.
+- **Trip highlights card** — a new card under the Trips summary surfaces standout trips in the current filter: most and least efficient, cheapest and priciest per 100 km/mi (only when every charge is priced), longest, biggest charging-overhead share, plus the total energy gap and average charging minutes per trip. Tap a highlight to jump straight to that trip.
+- **Battery health history** — the Battery screen now records a max-range snapshot each time it loads (once per day) and shows a trend chart with the last three months of data once enough snapshots exist.
+
 ### Changed
 - **Snappier throughout** — smoother list scrolling, lighter chart rendering, the Stats and Trips screens do their heavy work off the UI thread, and the dashboard stops polling for status while it's off screen (less background battery use). No change to how anything looks.
 - **Large cost totals now use a thousands separator** (e.g. "1,234.56") consistently across the stats, mileage and trip screens, matching how distances and energy are already shown.

README.md

@@ -15,7 +15,7 @@ A native Android application for viewing Tesla vehicle data from your self-hoste
 
 - **Dashboard** - Real-time vehicle status at a glance with 3D car image matching your vehicle's color and wheels. Long tap it to change the picture.
 - **Notifications** - Sentry events notification, tyres pressure alert and Live notification (Android 16+) of charging sessions.
-- **Widget** - Home/lock screen widget for easy and safe read-only access to your car status. No more trunks opened due to a misstap!
+- **Widgets** - Home/lock screen widgets for easy and safe read-only access to your car status (no more trunks opened due to a misstap!) and a Cost Summary widget showing your charging spend over the last 7, 30 or 90 days.
 - **Stats for Nerds** - Tap car image for advanced statistics: records, extremes, AC/DC ratio and much more!
 - **Charging History** - View all charging sessions with statistics and charts
 - **Charge Details** - Interactive map and detailed power/voltage/temperature charts