refactor: Move config from method parameters to InteractiveRunner struct field

[exileum]

Problem

The InteractiveRunner currently passes config as a parameter through multiple method calls, creating unnecessary coupling and inconsistent patterns compared to other structs in the codebase.

Current issues:

• Config parameter passed through 9+ method calls in InteractiveRunner
• Inconsistent with other structs (Runner, Migrator, PreflightChecker) which store config as fields
• Makes method signatures verbose and error-prone
• Harder to maintain and extend

Current pattern:

runner := migration.NewInteractiveRunner(*nonInteractive)
if err := runner.Run(cfg); err != nil { // Config passed as parameter

Proposed Solution

Refactor InteractiveRunner to store config as a struct field, consistent with existing architecture patterns.

Desired pattern:

runner := migration.NewInteractiveRunner(*nonInteractive, cfg)
if err := runner.Run(); err != nil { // No config parameter needed

Implementation Details

Files to modify:

1. internal/migration/interactive.go:

• Add config *config.Config field to InteractiveRunner struct
• Update constructor: NewInteractiveRunner(nonInteractive bool, cfg *config.Config) *InteractiveRunner
• Remove cfg *config.Config parameter from all methods:
  • Run(cfg *config.Config) → Run()
  • setProgressFile(cfg *config.Config, ...) → setProgressFile(...)
  • handlePreMigrationSteps(cfg *config.Config, ...) → handlePreMigrationSteps(...)
  • runMigration(cfg *config.Config, ...) → runMigration(...)
  • handlePostMigrationSteps(cfg *config.Config, ...) → handlePostMigrationSteps(...)
  • handleMigrationError(cfg *config.Config, ...) → handleMigrationError(...)
  • getLastProcessedID(cfg *config.Config, ...) → getLastProcessedID(...)
  • selectNewCategories(cfg *config.Config, ...) → selectNewCategories(...)
  • runDryRun(cfg *config.Config, ...) → runDryRun(...)
• Replace all cfg references with r.config in method bodies

2. cmd/xenforo-to-gh-discussions/main.go:

// Before
runner := migration.NewInteractiveRunner(*nonInteractive)
if err := runner.Run(cfg); err != nil {

// After  
runner := migration.NewInteractiveRunner(*nonInteractive, cfg)
if err := runner.Run(); err != nil {

3. Update any existing tests that use InteractiveRunner

Benefits

✅ Consistency: Aligns with existing patterns used by Runner, Migrator, PreflightChecker
✅ Cleaner interfaces: Methods focus on their logic, not parameter passing
✅ Maintainability: New methods automatically have config access
✅ Less error-prone: No risk of forgetting to pass config or passing wrong instance
✅ Single source of truth: Config stored once, accessible everywhere

Scope

• Small, focused refactoring affecting only InteractiveRunner
• No breaking changes to public APIs outside the migration package
• No changes needed to other structs (they already follow desired pattern)

Acceptance Criteria

• Config stored as InteractiveRunner struct field
• Constructor takes config parameter
• All methods updated to use r.config instead of parameter
• Method signatures cleaned up (no config parameters)
• Main.go updated to pass config to constructor
• All tests pass
• Pattern consistent with other migration structs