Tether 2.0.0

Superseded by 2.0.1, a security fix. Please install 2.0.1 instead, including its helper.

First public release.

• Clamshell mode follows power: on while connected, off on battery, and a Mac already closed is put
  to sleep the moment it's unplugged. Its switch turns it off until power is connected again.
• No lock: the screen under the lid is dimmed instead of sleeping the display. Optionally lock
  when the lid closes instead.
• Battery hold with safety limits enforced by the helper (battery temperature by lid state,
  thermal pressure, battery floor, time), adjustable only toward stricter values.
• Heat guard: Low Power Mode for a closed Mac running hot on power, and sleep if it keeps
  overheating with no display attached (a bag on a power bank counts as power).
• Low Power Mode only where you allow it (during battery holds; when hot on power, from "serious",
  from "fair" or never), and your own change to it is never undone.
• A watchdog LaunchDaemon that turns sleep back on if the helper ever stops while sleep is off on
  battery.
• A Mac put to sleep on power stays asleep through Power Nap's dark wakes; a charger that can't
  keep up can no longer run the battery flat with the lid closed; a battery hold can't start at or
  below the floor; the app relaunches after a crash.
• Data-based settings: time-weighted battery temperatures, battery use during holds, and
  recommended limits from them; "Adjust to this Mac" applies them by itself as measurements come
  in, never looser than the defaults.
• Sleep log: duration, charge per hour, sleep and wake causes, dark wakes; alerts on high drain.
• Screen off without locking after a few idle minutes.
• tether command with status --json, hold, sleep, run -- <command> and diagnose.
• tether:// URLs for the Shortcuts app.
• Apps keeping the Mac awake, live in Settings and tether status.
• Troubleshooting: detailed logging and a Markdown report with masked names, from Settings or
  tether diagnose --record.
• Control Center style panel (full and compact) with a clamshell switch and a countdown to the
  second; a status item with a ring that empties during a battery hold.
• Icon Composer app icon (Liquid Glass, dark, clear and tinted), sidebar settings, English and
  Korean with a choice in Settings.
• tether doctor and a checks list in Settings › System and at the top of the report; "+30m"
  for a running battery hold (tether hold +30m), still capped at 4 hours from its start.
• In-place help: an ⓘ next to each setting that needs explaining (what it does, the words it
  uses), Help › Tether Help opening the README, and a glossary in the README.
• First-run welcome, update check against GitHub releases, full uninstall.
• A quiet panel: controls that can't act right now are hidden rather than greyed out, and there
  are no lid-open or toggle notifications (the last lid session is in the panel and History).
• Desktop Macs are left alone.