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.

CONTRIBUTING.md

@@ -1,11 +1,11 @@
-# Contributing to WGX
+# Contributing to ihasvpn
 
 Thanks for your interest. Bug reports, feature requests, code and
 documentation are all welcome.
 
 ## Before you start
 
-- WGX is one container: the WireGuard server and the UI that manages it.
+- ihasvpn is one container: the WireGuard server and the UI that manages it.
   Contributions that need a second service (a database, a message queue, a
   separate frontend host) are out of scope.
 - The kernel data plane is the point. Anything on the packet path has to
@@ -22,7 +22,7 @@ You need Go (see `go.mod` for the version), Node 26 and Docker.
 cd web && npm ci && npm run dev
 
 # Backend against the in-memory mock data plane -- no privileges needed
-WGX_BACKEND=mock WGX_DATA_DIR=/tmp/wgx WGX_HTTP_LISTEN=127.0.0.1:51821 go run ./cmd/wgx
+IHASVPN_BACKEND=mock IHASVPN_DATA_DIR=/tmp/ihasvpn IHASVPN_HTTP_LISTEN=127.0.0.1:51821 go run ./cmd/ihasvpn
 ```
 
 The mock simulates peers handshaking and moving traffic so the dashboard has
@@ -30,9 +30,9 @@ something to show. For the real thing:
 
 ```sh
 cd web && npm run build && cd ..
-docker build -t wgx:dev .
+docker build -t ihasvpn:dev .
 docker run --rm --cap-add NET_ADMIN --sysctl net.ipv4.ip_forward=1 \
-  -p 51820:51820/udp -p 127.0.0.1:51821:51821 -v wgx-dev:/data wgx:dev
+  -p 51820:51820/udp -p 127.0.0.1:51821:51821 -v ihasvpn-dev:/data ihasvpn:dev
 ```
 
 ## Before you commit
@@ -42,7 +42,7 @@ CI checks are not a substitute for building locally. Run, in this order:
 ```sh
 cd web && npm run build && cd ..     # type-checks and builds the UI
 go vet ./... && go test -count=1 ./...
-docker build -t wgx:dev .            # when the change reaches the image
+docker build -t ihasvpn:dev .            # when the change reaches the image
 ```
 
 `go test` covers the engine against the mock data plane and the whole HTTP