refactor: cleanup god-function duplication and dead code

[aaight]

Summary

• Extract shared wizard components — Created web/src/components/projects/wizard-shared.tsx with WizardStep, InlineCredentialCreator, and CredentialOption shared across all three wizard files, eliminating ~250 lines of verbatim duplication across pm-wizard.tsx, email-wizard.tsx, and twilio-wizard.tsx.
• Extract Gmail OAuth DB logic into repository layer — Added upsertCredentialByEnvVarKey and upsertGmailIntegrationWithCredentials to credentialsRepository.ts, removing ~100 lines of duplicated find-or-create + update patterns from integrationsDiscovery.ts.
• Delete deprecated backend shims — Removed src/backends/agent-profiles.ts and src/backends/toolManifests.ts (both were pure re-export shims), updated all consumers (source files and tests) to import directly from canonical locations (src/agents/definitions/profiles.ts and src/agents/definitions/toolManifests.ts).
• Remove deprecated trigger config aliases — Deleted IssueTransitionedSchema, IssueTransitionedConfig, and resolveIssueTransitionedEnabled from triggerConfig.ts; removed the corresponding deprecated-alias test suite.

Card: https://trello.com/c/69ab5027594361a9f9273023

Test plan

• All 3,841 unit tests pass
• TypeScript type checking passes (no errors)
• Biome lint passes (no errors)
• triggerConfig.test.ts — 112 tests pass (deprecation alias suite removed)
• backends/adapter.test.ts — 34 tests pass (mock updated for canonical import)
• backends/agent-profiles.test.ts — tests pass with canonical import path
• backends/toolManifests.test.ts — tests pass with canonical import path

🤖 Generated with Claude Code

[nhopeatall]

Summary

Clean refactoring PR that eliminates real duplication without changing behavior. All four changes are straightforward and correct — shared wizard components unify three near-identical implementations, the Gmail credential logic moves to the right layer (repository), and the deprecated shims/aliases are safe to remove with no remaining consumers.

All CI checks pass (lint, type-check, 3,841 unit tests, integration tests).