Rename the project to ihasvpn

WGX shares its name with several other WireGuard tools, so the project
becomes ihasvpn, alongside ihasmail.

- Module github.com/Coffey-Labs/ihasvpn, command cmd/ihasvpn, image
  ghcr.io/coffey-labs/ihasvpn.
- Environment variables move from WGX_* to IHASVPN_*. The default database
  is ihasvpn.db, the nftables table is `ihasvpn`, metrics are ihasvpn_*, and
  the session cookie and theme key are renamed, so existing sessions end.
- The mark is the ihasmail cat peeking over the edge of a shield, drawn as
  a vector. docs/brand/generate.py builds the mark, mono mark, wordmarks,
  social card, favicons and app icons from that one drawing.
- The console takes ihasmail's palette: the ihasmail.org teal-navy for dark,
  its contrast-checked light tiers with the site's light accent, received
  traffic in the cat's orange and sent in teal. The wordmark weight and
  font stack follow ihasmail.org.
- Detail values wrap at spaces before breaking inside an address, so an
  IPv6 tunnel address no longer splits mid-number.
- The README history note about the earlier WGX installer is gone with the
  name it explained. Screenshots retaken.

Dockerfile

@@ -10,14 +10,14 @@ RUN npm run build
 FROM golang:1.27-alpine AS build
 # The version string the binary reports. Worked out by whoever runs the
 # build (CI passes the tag); left empty it says "dev".
-ARG WGX_VERSION=dev
+ARG IHASVPN_VERSION=dev
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download
 COPY cmd/ cmd/
 COPY internal/ internal/
 COPY --from=web /src/internal/server/static/dist internal/server/static/dist
-RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w -X github.com/Coffey-Labs/WGX/internal/engine.Version=${WGX_VERSION}" -o /wgx ./cmd/wgx
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w -X github.com/Coffey-Labs/ihasvpn/internal/engine.Version=${IHASVPN_VERSION}" -o /ihasvpn ./cmd/ihasvpn
 
 # ---- runtime ----
 FROM alpine:3.22
@@ -25,11 +25,11 @@ FROM alpine:3.22
 # without the kernel module; wireguard-tools gives `wg show` for debugging.
 RUN apk add --no-cache nftables wireguard-go wireguard-tools ca-certificates tzdata \
     && mkdir -p /data
-COPY --from=build /wgx /usr/local/bin/wgx
-ENV WGX_DATA_DIR=/data \
-    WGX_HTTP_LISTEN=:51821
+COPY --from=build /ihasvpn /usr/local/bin/ihasvpn
+ENV IHASVPN_DATA_DIR=/data \
+    IHASVPN_HTTP_LISTEN=:51821
 VOLUME ["/data"]
 EXPOSE 51820/udp 51821/tcp
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s \
     CMD wget -qO- http://127.0.0.1:51821/api/health || exit 1
-ENTRYPOINT ["wgx"]
+ENTRYPOINT ["ihasvpn"]