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.

.github/workflows/ci.yml

@@ -30,4 +30,4 @@ jobs:
       - name: govulncheck
         run: go run golang.org/x/vuln/cmd/govulncheck@latest ./...
       - name: Docker build
-        run: docker build -t wgx:ci .
+        run: docker build -t ihasvpn:ci .

.github/workflows/publish.yml

@@ -25,7 +25,7 @@ on:
         default: false
 
 env:
-  IMAGE: ghcr.io/coffey-labs/wgx
+  IMAGE: ghcr.io/coffey-labs/ihasvpn
 
 jobs:
   version:
@@ -74,7 +74,7 @@ jobs:
         with:
           context: .
           platforms: ${{ matrix.platform }}
-          build-args: WGX_VERSION=${{ needs.version.outputs.version }}
+          build-args: IHASVPN_VERSION=${{ needs.version.outputs.version }}
           provenance: false
           sbom: false
           cache-from: type=gha,scope=${{ matrix.platform }}