Rebrand: Nexus Terminal → Alchementary Link

Renames the product across the codebase: Go module path, config/data
paths, keychain service name, export file extension, build tooling,
docs, and UI text. Sidebar brand mark now reads ">_ AlchementaryLink"
with "Alchementary" in the connection-group gold accent colour, and
the window title is "Alchementary Link".

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019T8bJS8BCtY5GeSG2HBj1n

internal/storage/migrations/001_initial.sql

@@ -1,4 +1,4 @@
--- Initial schema for Nexus Terminal
+-- Initial schema for Alchementary Link
 -- Creates the core tables for profiles, known hosts, preferences, and audit log.
 
 CREATE TABLE IF NOT EXISTS profiles (

internal/storage/storage_test.go

@@ -7,7 +7,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/andydixon/nexus/internal/models"
+	"github.com/andydixon/link/internal/models"
 	"github.com/google/uuid"
 )
 
@@ -37,8 +37,8 @@ func makeIRCProfile(name, host string) *models.Profile {
 	p := models.NewProfile(models.ProtocolIRC)
 	p.DisplayName = name
 	p.Host = host
-	p.Username = "nexus"
-	p.IRC.Nick = "nexus"
+	p.Username = "link"
+	p.IRC.Nick = "link"
 	return &p
 }
 
@@ -120,14 +120,14 @@ func TestIRCLastRoomsRoundTripReplaceAndDelete(t *testing.T) {
 		t.Fatalf("CreateProfile() error = %v", err)
 	}
 
-	if err := store.SaveIRCLastRooms(p.ID, []string{" #Go-Nuts ", "#nexus", "#go-nuts", ""}); err != nil {
+	if err := store.SaveIRCLastRooms(p.ID, []string{" #Go-Nuts ", "#link", "#go-nuts", ""}); err != nil {
 		t.Fatalf("SaveIRCLastRooms() error = %v", err)
 	}
 	rooms, err := store.GetIRCLastRooms(p.ID)
 	if err != nil {
 		t.Fatalf("GetIRCLastRooms() error = %v", err)
 	}
-	if got, want := strings.Join(rooms, ","), "#Go-Nuts,#nexus"; got != want {
+	if got, want := strings.Join(rooms, ","), "#Go-Nuts,#link"; got != want {
 		t.Fatalf("GetIRCLastRooms() = %q, want %q", got, want)
 	}
 

internal/storage/store.go

@@ -11,8 +11,8 @@ import (
 
 	_ "modernc.org/sqlite"
 
-	"github.com/andydixon/nexus/internal/models"
-	"github.com/andydixon/nexus/internal/storage/migrations"
+	"github.com/andydixon/link/internal/models"
+	"github.com/andydixon/link/internal/storage/migrations"
 	"github.com/google/uuid"
 )