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

.golangci.yml

@@ -0,0 +1,29 @@
+# golangci-lint configuration
+# https://golangci-lint.run/usage/configuration/
+
+run:
+  timeout: 5m
+  tests: true
+
+linters:
+  enable:
+    - errcheck
+    - gosimple
+    - govet
+    - ineffassign
+    - staticcheck
+    - unused
+    - gosec
+    - gocritic
+    - gofmt
+
+linters-settings:
+  govet:
+    enable:
+      - fieldalignment
+  gosec:
+    excludes:
+      - G304 # File path provided as taint input - handled with #nosec comments where needed
+  gocritic:
+    disabled-checks:
+      - ifElseChain # Complex conditionals are clearer as if-else than switch true