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.

internal/server/server_test.go

@@ -14,11 +14,11 @@ import (
 	"testing"
 	"time"
 
-	"github.com/Coffey-Labs/WGX/internal/auth"
-	"github.com/Coffey-Labs/WGX/internal/config"
-	"github.com/Coffey-Labs/WGX/internal/engine"
-	"github.com/Coffey-Labs/WGX/internal/store"
-	"github.com/Coffey-Labs/WGX/internal/wg"
+	"github.com/Coffey-Labs/ihasvpn/internal/auth"
+	"github.com/Coffey-Labs/ihasvpn/internal/config"
+	"github.com/Coffey-Labs/ihasvpn/internal/engine"
+	"github.com/Coffey-Labs/ihasvpn/internal/store"
+	"github.com/Coffey-Labs/ihasvpn/internal/wg"
 )
 
 type client struct {
@@ -178,7 +178,7 @@ func TestSetupLoginAndPeers(t *testing.T) {
 	req.Header.Set("Authorization", "Bearer metrics-secret")
 	r, _ := anon.Do(req)
 	b, _ := io.ReadAll(r.Body)
-	if r.StatusCode != 200 || !strings.Contains(string(b), "wgx_peers ") {
+	if r.StatusCode != 200 || !strings.Contains(string(b), "ihasvpn_peers ") {
 		t.Fatalf("token metrics: %d %s", r.StatusCode, b)
 	}
 }