refactor: remove cached AppConfig pointer and read configuration directly from DB

Replace in-memory atomic AppConfig caching with direct DB queries via db.GetConfig
across application and page layers. This simplifies state management and ensures
all components always operate on the latest persisted configuration.

Key changes:
- Remove Application.Config atomic cache and refreshCache mechanism
- Eliminate PageCtx.CfgPtr and pass DB handle instead
- Replace all cfg reads with db.GetConfig(app.DB)
- Update mixer, audio, UI pages, and initialization paths accordingly
- Explicitly set AppConfig table name to avoid GORM pluralization issues
- Reduce DB connection pooling (SetMaxIdleConns(1))
- Standardize application font to SpaceMonoNerdFont-Regular
- Lower default audio volume (1.0 → 0.2)
- Add Unicode checkmark glyph to font map

Behavioral impact:
- Configuration is no longer cached in memory
- Every config access now hits the DB (more consistent, slightly more overhead)

internal/page/licenseKeyPage.go

@@ -10,6 +10,7 @@ import (
 	"github.com/go-gl/mathgl/mgl32"
 	"github.com/veandco/go-sdl2/sdl"
 	"rhemawavetech.com/rhemawave/internal/colors"
+	"rhemawavetech.com/rhemawave/internal/db"
 	"rhemawavetech.com/rhemawave/internal/fontManager"
 	"rhemawavetech.com/rhemawave/internal/logger"
 	"rhemawavetech.com/rhemawave/internal/shaderManager"
@@ -55,7 +56,7 @@ func (p *LicenseKeyPage) Init(ctx *PageCtx) error {
 	p.title = "License Key"
 
 	// Get application font from database
-	applicationFont := "Roboto-Regular"
+	applicationFont := "SpaceMonoNerdFont-Regular"
 
 	fm := fontManager.Get()
 	textShader, ok := shaderManager.Get().Get("text")
@@ -77,7 +78,11 @@ func (p *LicenseKeyPage) Init(ctx *PageCtx) error {
 	p.titleTextureHeight = titleHeight
 
 	// Load existing license key from database
-	licenseKey := p.Context.CfgPtr.LicenseKey
+	config, err := db.GetConfig(p.Context.DbPtr)
+	if err != nil {
+		panic(err)
+	}
+	licenseKey := config.LicenseKey
 
 	if licenseKey != "" {
 		p.inputText = licenseKey
@@ -188,9 +193,12 @@ func (p *LicenseKeyPage) HandleEvent(event *sdl.Event) error {
 				sdl.StopTextInput()
 
 				// Save license key to database
-				p.Context.CfgPtr.LicenseKey = p.inputText
-				p.Context.DbPtr.Save(p.Context.CfgPtr)
-				p.Context.RefreshConfig()
+				config, err := db.GetConfig(p.Context.DbPtr)
+				if err != nil {
+					panic(err)
+				}
+				config.LicenseKey = p.inputText
+				p.Context.DbPtr.Save(config)
 
 				// Write license key to plain text file for the updater
 				if homeDir, err := os.UserHomeDir(); err == nil {
@@ -239,7 +247,7 @@ func (p *LicenseKeyPage) HandleEvent(event *sdl.Event) error {
 // Update updates animations and changing textures and other changes using `dt` which represents a time delta in float32.
 func (p *LicenseKeyPage) Update(dt float32) error {
 	// Get application font from database
-	applicationFont := "Roboto-Regular"
+	applicationFont := "SpaceMonoNerdFont-Regular"
 
 	fm := fontManager.Get()
 	sm := shaderManager.Get()
@@ -302,8 +310,12 @@ func (p *LicenseKeyPage) Update(dt float32) error {
 
 // Render performs page drawing logic.
 func (p *LicenseKeyPage) Render() error {
+	config, err := db.GetConfig(p.Context.DbPtr)
+	if err != nil {
+		panic(err)
+	}
 	// Get base font size from database
-	baseFontSize := p.Context.CfgPtr.StandardFontSize
+	baseFontSize := config.StandardFontSize
 
 	sm := shaderManager.Get()