style: Extract UI constants and refactor main view rendering (#30)

- [x] Add golangci-lint configuration with gocritic ifElseChain disabled
- [x] Rename error variables to avoid shadowing (createErr, watcherErr, watchErr, etc.)
- [x] Replace `interface{}` with `any` type alias throughout codebase
- [x] Add package-level documentation comments to all internal packages
- [x] Reorder struct fields alphabetically for consistency
- [x] Extract UI constants (terminal dimensions, column widths, colors) to constants.go
- [x] Refactor BubbleTeaUI main view rendering into smaller helper functions
- [x] Simplify nested conditionals and improve code clarity
- [x] Add `isForwardDisabled()` helper method to BubbleTeaUI
- [x] Update file permissions from 0644 to 0600 in config tests
- [x] Add `#nosec` comments and error suppression where appropriate
- [x] Improve test table struct field ordering for readability
- [x] Fix resource parsing in AddForward using strings.SplitN
- [x] Add comprehensive tests for new UI helper functions and constants

internal/ui/constants.go

@@ -0,0 +1,45 @@
+package ui
+
+// Terminal dimension constants
+const (
+	// DefaultTermWidth is the fallback terminal width when not detected
+	DefaultTermWidth = 120
+
+	// DefaultTermHeight is the fallback terminal height when not detected
+	DefaultTermHeight = 40
+)
+
+// Table column constants
+const (
+	// Column indices in the forwards table
+	ColumnContext   = 0
+	ColumnNamespace = 1
+	ColumnAlias     = 2
+	ColumnType      = 3
+	ColumnResource  = 4
+	ColumnRemote    = 5
+	ColumnLocal     = 6
+	ColumnStatus    = 7
+
+	// Column widths for truncation
+	ColumnWidthContext   = 14
+	ColumnWidthNamespace = 16
+	ColumnWidthAlias     = 18
+	ColumnWidthType      = 8
+	ColumnWidthResource  = 20
+
+	// Error display widths
+	ErrorDisplayWidth = 118 // Slightly less than table width (120) for padding
+)
+
+// Viewport constants
+const (
+	// ViewportHeight is the number of items visible in list views
+	ViewportHeight = 20
+)
+
+// Path display constants
+const (
+	// MaxPathWidth is the maximum width for displaying file paths
+	MaxPathWidth = 48
+)