refactor(pm-wizard): split 1,679-line god component into modular structure

[aaight]

Summary

Refactors the 1,679-line PM wizard god component into a modular, maintainable structure without any behavioral changes.

• pm-wizard.tsx: 1,679 → 298 lines — now a thin orchestrator that calls extracted hooks and delegates rendering to sub-components
• pm-wizard-state.ts (new): All types, constants (INITIAL_JIRA_LABELS), createInitialState(), wizardReducer, step-completion helpers, and buildEditState() — zero imports from other pm-wizard files
• pm-wizard-hooks.ts (new): useTrelloDiscovery, useJiraDiscovery, useVerification, useWebhookManagement, useSaveMutation — each hook encapsulates one concern
• pm-wizard-trello-steps.tsx (new): TrelloCredentialsStep, TrelloBoardStep, TrelloFieldMappingStep
• pm-wizard-jira-steps.tsx (new): JiraCredentialsStep, JiraProjectStep, JiraFieldMappingStep
• pm-wizard-common-steps.tsx (new): WebhookStep, SaveStep (provider-agnostic)
• wizard-shared.tsx (updated): Added SearchableSelect and FieldMappingRow components from the original file — now shared across all wizard consumers

Test plan

• 44 new unit tests for wizardReducer, step-completion helpers, buildEditState, and areCredentialsReady
• Full test suite passes (3,885 tests, zero failures)
• TypeScript type check passes (zero errors)
• Biome lint passes (zero errors)
• All biome-ignore complexity overrides justified with clear comments

Trello card: https://trello.com/c/69abb7e4b94a126e439d0041

🤖 Generated with Claude Code

[nhopeatall]

Summary

LGTM — This is a clean, well-executed decomposition of a 1,679-line god component into 6 focused modules with no behavioral changes.

The module structure follows a sensible dependency graph: pm-wizard-state.ts (pure state, zero imports from other pm-wizard files) → pm-wizard-hooks.ts (side-effects) → pm-wizard.tsx (orchestrator), with step components importing only from pm-wizard-state and wizard-shared. No circular dependencies.

The extraction is mechanical and faithful — I verified the code in each new file matches the removed sections line-by-line. The 44 new unit tests cover all the pure functions that were previously untestable because they were embedded in the component. All CI checks pass.