Add Go project scaffold for Wails v2 SSH/Telnet/RAW TCP client

- go.mod with Wails v2.9.2, x/crypto, go-sqlite3, go-keyring, uuid
- cmd/app/main.go: Wails entry point (Nexus Terminal, 1400x900, #1a1a2e)
- internal/app/app.go: lifecycle (Startup/Shutdown/DomReady)
- internal/models/models.go: full model definitions (Profile, SSHConfig,
  TelnetConfig, RAWConfig, SessionInfo, KnownHost, AppPreferences, etc.)
- internal/models/defaults.go: default values and NewProfile factory
- internal/validation/validation.go: thorough field-level validation
- frontend/embed.go: embedded frontend assets
- Updated existing storage, secrets, config to match new model structure

internal/storage/migrations/001_initial.sql

@@ -0,0 +1,63 @@
+-- Initial schema for Nexus Terminal
+-- Creates the core tables for profiles, known hosts, preferences, and audit log.
+
+CREATE TABLE IF NOT EXISTS profiles (
+    id TEXT PRIMARY KEY,
+    display_name TEXT NOT NULL,
+    description TEXT DEFAULT '',
+    protocol TEXT NOT NULL CHECK(protocol IN ('ssh', 'telnet', 'raw')),
+    host TEXT NOT NULL,
+    port INTEGER NOT NULL,
+    username TEXT DEFAULT '',
+    tags TEXT DEFAULT '[]',
+    folder TEXT DEFAULT '',
+    environment TEXT DEFAULT '',
+    notes TEXT DEFAULT '',
+    favourite INTEGER DEFAULT 0,
+    last_connected TEXT,
+    connect_timeout INTEGER DEFAULT 30,
+    read_timeout INTEGER DEFAULT 0,
+    terminal_font_family TEXT DEFAULT '',
+    terminal_font_size INTEGER DEFAULT 0,
+    terminal_scrollback INTEGER DEFAULT 0,
+    terminal_cursor_style TEXT DEFAULT '',
+    ssh_config TEXT,
+    telnet_config TEXT,
+    raw_config TEXT,
+    created_at TEXT NOT NULL,
+    updated_at TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS known_hosts (
+    id TEXT PRIMARY KEY,
+    host TEXT NOT NULL,
+    port INTEGER NOT NULL,
+    key_type TEXT NOT NULL,
+    fingerprint TEXT NOT NULL,
+    public_key TEXT NOT NULL,
+    first_seen TEXT NOT NULL,
+    last_seen TEXT NOT NULL,
+    trusted INTEGER DEFAULT 1,
+    UNIQUE(host, port, key_type)
+);
+
+CREATE TABLE IF NOT EXISTS preferences (
+    key TEXT PRIMARY KEY,
+    value TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS audit_log (
+    id TEXT PRIMARY KEY,
+    timestamp TEXT NOT NULL,
+    action TEXT NOT NULL,
+    profile_id TEXT DEFAULT '',
+    session_id TEXT DEFAULT '',
+    details TEXT DEFAULT ''
+);
+
+CREATE TABLE IF NOT EXISTS schema_version (
+    version INTEGER PRIMARY KEY,
+    applied_at TEXT NOT NULL
+);
+
+INSERT OR IGNORE INTO schema_version (version, applied_at) VALUES (1, datetime('now'));

internal/storage/migrations/migrations.go

@@ -0,0 +1,10 @@
+// Package migrations provides embedded SQL migration files for the storage layer.
+package migrations
+
+import "embed"
+
+// MigrationFS contains all embedded SQL migration files.
+// Each migration is numbered sequentially (e.g. 001_initial.sql).
+//
+//go:embed *.sql
+var MigrationFS embed.FS