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/auth_http.go

@@ -10,11 +10,11 @@ import (
 
 	"github.com/skip2/go-qrcode"
 
-	"github.com/Coffey-Labs/WGX/internal/auth"
-	"github.com/Coffey-Labs/WGX/internal/store"
+	"github.com/Coffey-Labs/ihasvpn/internal/auth"
+	"github.com/Coffey-Labs/ihasvpn/internal/store"
 )
 
-const cookieName = "wgx_session"
+const cookieName = "ihasvpn_session"
 
 type ctxKey int
 
@@ -450,7 +450,7 @@ func (s *Server) handleTOTPSetup(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusInternalServerError, err.Error())
 		return
 	}
-	writeJSON(w, http.StatusOK, totpSetupResponse{Secret: secret, URI: auth.TOTPURI("WGX", u.Username, secret)})
+	writeJSON(w, http.StatusOK, totpSetupResponse{Secret: secret, URI: auth.TOTPURI("ihasvpn", u.Username, secret)})
 }
 
 // handleTOTPQR renders the pending secret's otpauth URI as a QR code. Only a
@@ -462,7 +462,7 @@ func (s *Server) handleTOTPQR(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusNotFound, "no two-factor setup in progress")
 		return
 	}
-	png, err := qrcode.Encode(auth.TOTPURI("WGX", u.Username, u.TOTPSecret), qrcode.Medium, 256)
+	png, err := qrcode.Encode(auth.TOTPURI("ihasvpn", u.Username, u.TOTPSecret), qrcode.Medium, 256)
 	if err != nil {
 		writeError(w, http.StatusInternalServerError, err.Error())
 		return