Ongoing notification: stable metrics in the title, volatile details in the body

[almothafar]

Problem

The persistent status notification's title was hard-coded to the app name — but Android already prints the app name in the notification header, so the boldest, most glanceable line was pure repetition.

Change

The two lines are now split by stability, with no redundancy between them:

• Title — the stable, always-available headline: percentage + plain charge state, e.g. 85% · Discharging / 85% · Charging. No app name, no rate, no tier (those move to the body).
• Content — the volatile details, each shown only when available, joined by ·:
  • the drain rate (9%/h, or the raw mA) while discharging, or the charge power (~18 W) while charging;
  • the estimated time to empty/full (~9h 27m left / ~45m to full), the same capacity-free projection the details table uses (Charging: time-to-full as a details-table row (rescoped — no standalone feature) #124/Details table: stop rows showing/hiding — keep Rate / Time / Current always present with a placeholder + info icon #188);
  • the temperature.
  • e.g. 9%/h · ~9h 27m left · 34.6 °C or ~18 W · ~45m to full · 34.6 °C, degrading gracefully down to just the temperature.

The charging body shows the wattage without the "Fast charging" tier word, because the title already says the phone is charging — so the title and body never repeat each other.

Details:

• The "Show rate in status notification" toggle is renamed "Show rate & time in status notification" and its summaries now match what it governs (the rate/power + the time estimate; the temperature always shows). Turning it off yields 85% · Discharging + temperature.
• statusWithRate / chargingSpeedSegment are removed (the title no longer needs them); the charge-tier label stays only on the separate charge-connected popup. New wattage-only string; the old tier+wattage and 2-part detail strings dropped. showRateEnabled is read once per build (was twice).
• New/changed strings in values/ and values-ar/ (Arabic drafted — pending maintainer review).

Testing

• NotificationServiceTest.OngoingStatusLines (6 tests): stable title from the built notification; discharging rate+time+temp; charging watts+time+temp; charge-rate fallback when power is unknown; temperature-only when the toggle is off; unknown title + empty detail on a null snapshot.
• Full :app:testDebugUnitTest (435) + lintDebug pass on the local toolchain; installed on the Mate 10 Pro.

Supersedes the original single-commit version (which put the rate in the title); reworked per review.