[dylanneve1]

The app side of networking milestone 2 (docs/NETWORKING.md).

What it does:

• Settings › Advanced › Network (QEMU), per install, off by default (qemu_network in the install list; lists written before it read as off).
• Off: the QEMU command line is unchanged, with the inferno uplink on the unix socket and no -netdev. QemuCommandTest compares it with a hand-written copy of the old command line. That test passed against main's QemuCommand.build before any change.
• On: normal boots get -netdev user,id=n0 and usb-uplink-type=net,usb-uplink-addr=n0. Restore boots (a ramdisk= in vm.properties) always keep the inferno uplink. I left out hostfwd (it would open a listening TCP port on the phone); it can be added when something needs SSH.
• DNS: with the setting on, QemuNet.Resolver writes the default network's LinkProperties.getDnsServers() to files/run/<id>/resolv.conf (nameserver ... lines, %ifname on link-local IPv6). It replaces the file with a rename when the network changes and deletes it when there is no server. QEMU gets the path in SLIRP_RESOLV_CONF, in the child's environment or via Os.setenv in the :vm process. This is the interface of PR 146 (Android build: enable libslirp (-netdev user) and fix DNS on Android #82, libslirp in the Android build).
• Status card: "Network: off", "Network: waiting for guest", "Network: guest has 10.0.2.15" while a QEMU VM runs, and "Network: off for restore boots" for a restore boot with the setting on. The connected state comes from Inferno's usb-net-uplink: guest reports network connected line. The address comes from slirp's info usernet on the monitor, polled every 3 s until it is found.
• Manifest: adds ACCESS_NETWORK_STATE. INTERNET was already declared for AVF's Network setting; its comment now covers both.
• Docs: a PHONE-QUICKSTART "Network (QEMU)" section and settings-table row, ETHICS point 7 and a README paragraph ("doesn't use the network unless you turn Network on"), and a "done in the app" note in NETWORKING.md.
• Refactors: AppPaths has a constructor from plain directories so the command line can be tested on the JVM; existing AppPaths(ctx, id) callers are unchanged. InstallMigration.seen is now built from the legacy keys alone. With a 13th key, org.json's JVM HashMap reorders, which broke InstallMigrationTest (on Android, where org.json keeps insertion order, the string is the same as before).

Depends on PR 146 for the network to work: without libslirp, QEMU with the setting on exits at once on -netdev user. With the setting off, nothing depends on it, so this can land before or after PR 146.

The AVF backend and native/build-android.sh are untouched.

Tested:

• ./gradlew lint testDebugUnitTest locally: 42 tests pass (8 new in QemuCommandTest), and lint reports only warnings that were already there.
• Emulator: see the comment below for results.

Not tested (left for Dylan, needs a Pixel 10 and PR 146):

• With the setting on, iOS 14 gets a lease and Safari loads a page.
• With it off, nothing opens an AF_INET socket during a full boot (ss -tuanp / lsof -i).
• The status line reaching "guest has 10.0.2.15" (needs a booting guest with the network).

Closes #83

[dylanneve1]

Emulator check (shared AVD "iop", sdk_gphone64_arm64), with this PR's CI APK installed fresh after an uninstall:

• dumpsys package: INTERNET and ACCESS_NETWORK_STATE are both declared and granted.
• Settings › Advanced shows "Network (QEMU)", off on a fresh install. Turning it on writes "qemu_network":true to installs.xml straight away, and it's still on after a force-stop and relaunch.
• I used a placeholder VM folder: zero-filled files, plus hand-made DER headers so the IMG4 checks pass. There are no Apple files in it. QEMU builds its command line from it, then crashes on the contents.
  • Setting off: files/run/1/last_run.txt shows -M t8030,...,kaslr-off=true,usb-uplink-type=inferno,usb-uplink-addr=unix:.../files/run/1/usb-uplink.sock, with no -netdev and no network: line in the output.
  • Setting on: the output starts with network: on (slirp behind the guest's USB link) and network: DNS through fec0::3, 10.0.2.3, 10.0.2.4, 10.0.2.5 (the emulator's own DNS servers, from LinkProperties). The command line has usb-uplink-type=net,usb-uplink-addr=n0 and -netdev user,id=n0. QEMU then exits with -netdev user,id=n0: network backend 'user' is not compiled into this binary, which is expected until PR 146 is in. resolv.conf was removed when QEMU exited.
• I didn't see the status line live: QEMU exited too fast with the placeholder files. Its text is covered by QemuCommandTest.statusLine.

Not done here, so left for Dylan: the Pixel 10 test with PR 146 (a lease, and Safari loading a page with the setting on), and ss/lsof during a real boot with it off.