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/retry/backoff.go

@@ -1,3 +1,19 @@
+// Package retry provides exponential backoff with jitter for retry logic.
+// It implements a backoff sequence of 1s → 2s → 4s → 8s → 10s (max),
+// with 10% random jitter to prevent thundering herd problems.
+//
+// Basic usage:
+//
+//	backoff := retry.NewBackoff()
+//	for {
+//	    err := doSomething()
+//	    if err == nil {
+//	        backoff.Reset()
+//	        break
+//	    }
+//	    delay := backoff.Next()
+//	    time.Sleep(delay)
+//	}
 package retry
 
 import (
@@ -19,8 +35,8 @@ const (
 // Backoff implements exponential backoff with jitter for retry logic.
 // The backoff sequence is: 1s → 2s → 4s → 8s → 10s (max, then stays at 10s).
 type Backoff struct {
-	attempt int
 	rng     *rand.Rand
+	attempt int
 }
 
 // NewBackoff creates a new Backoff instance with a seeded random number generator.
@@ -53,7 +69,7 @@ func (b *Backoff) Next() time.Duration {
 
 	// Add jitter (±10%)
 	jitter := b.calculateJitter(delay)
-	delay = delay + jitter
+	delay += jitter
 
 	b.attempt++
 	return delay