rebrand: podkop -> NetShift (v0.8.0) with migration

Full project rebrand to reduce association with upstream podkop, per
upstream maintainers' request.

Renames (git mv, history preserved):
- package podkop -> netshift (/usr/bin/netshift, /etc/config/netshift,
  /etc/init.d/netshift, /etc/netshift state dir, /usr/lib/netshift)
- luci-app-podkop -> luci-app-netshift; view namespace view/podkop -> view/netshift
- fe-app-podkop -> fe-app-netshift; TS namespace Podkop -> NetShift
- nft table PodkopTable -> NetShiftTable; rt_table podkop -> netshift
- nft sets, dnsmasq backup keys, cron self-calls, PID/tmp paths
- i18n podkop.pot/po -> netshift.pot/po; web title Podkop -> NetShift
- build-arg PODKOP_VERSION -> NETSHIFT_VERSION; Dockerfiles + CI workflows

Migration (install.sh migrate_from_podkop): on detecting an old podkop
install, stops the old service (clean teardown of nft/dnsmasq/rt_tables),
copies /etc/config/podkop -> /etc/config/netshift (backup at
/etc/config/podkop.bak.pre-netshift), migrates state dir, strips old
cron/rt_tables entries, removes old packages, then installs NetShift.
Config schema is compatible so the VPN keeps working after migration.

Docs: README + TRADEMARK rewritten for NetShift.

Intentionally kept: upstream attribution (itdoginfo/podkop), podkop.net
docs links, *.podkop.fyi check domains, yandexru45/podkop-evolution repo
URL (GitHub repo not renamed yet), maintainer email.

Verified: bash -n clean, yarn lint/test (283) pass, main.js idempotent,
Docker ipk build produces netshift_v0.8.0 / luci-app-netshift_v0.8.0.

fe-app-netshift/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ESNext",
+    "strict": true,
+    "moduleResolution": "node",
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "outDir": "dist"
+  },
+  "include": ["src"]
+}