fix(docker): let Provider Settings admit the host through the published port

Docker delivers the host's own browser to the container from the container
network's gateway, never from 127.0.0.1, so the loopback-only admission gate
answered every POWER UP request with 403 and no key could be saved. The README
and CHANGELOG claimed otherwise; both are corrected here.

- keySetupCore: GEV_KEY_SETUP_TRUSTED_PEERS, an exact-address list (no
  wildcards, prefixes or hostnames) admitted alongside loopback. Unset trusts
  nothing, and the sharing, Host, Origin, Content-Type and proxy-header checks
  all still apply to a listed address. Twelve assertions pin each refusal.
- scripts/docker-start.mjs: the container entry point, shaped after
  scripts/pinokio-start.mjs. It reads the default gateway from /proc/net/route,
  trusts exactly that address, and starts Vite. No gateway (--network none)
  trusts nothing. The pure helpers are unit-tested and a contract test pins the
  Dockerfile CMD and the loopback-only publish.
- Dockerfile: install git. `npm test` builds fixtures with `git init`, so the
  suite failed 71 tests inside the image and the README's claim that it runs in
  the container was wrong.
- SECURITY.md and .env.example document the setting and why it is safe only
  behind a 127.0.0.1 publish; README gains the Linux/NAS id note and .dockerignore
  drops macOS AppleDouble sidecars, both reported on the PR.

Verified in Docker on a clean build: saving a key from the panel writes the
bind-mounted .env (0600 in the container), it survives `compose down`/`up`, and
REMOVE comments it back out. A foreign Origin, a foreign Host, a proxy header
and a sibling container on the same network are each refused. `npm run doctor`,
`npm test` (5067 passed, 1 skipped, 0 failed) and `npm run build` are green
inside the container.

Reported-by: @jklaze
Co-Authored-By: Bogdan Petrut <[email protected]>
Co-Authored-By: Claude Opus 5 <[email protected]>

.env.example

@@ -95,6 +95,13 @@ OPENAI_HUD_SUMMARY_MODEL=gpt-5-nano
 # spend protection set a provider-side budget: OpenAI platform -> Settings ->
 # Limits (usage limits).
 # GEV_RATELIMIT_OPENAI_PER_MIN=30   # the default; uncomment only to change it
+# Optional: exact socket addresses (comma-separated, no wildcards or prefixes)
+# that Provider Settings treats as this machine in addition to loopback. Leave
+# unset. The Docker launcher sets it to the container's gateway at start,
+# because that is where Docker delivers your own browser from; it is safe only
+# while the port is published on 127.0.0.1. Read SECURITY.md before setting it
+# by hand.
+# GEV_KEY_SETUP_TRUSTED_PEERS=
 
 # Optional: Mapillary imagery for the Street Level layer. Free client token from
 # https://www.mapillary.com/dashboard/developers (register an app, copy its