feat(init): rewrite init CLI transport for Vercel Workflows

[betegon]

Summary

This rewrites the sentry init CLI transport to talk to the new Vercel Workflows backend.

Instead of the old Mastra createRun/startAsync/resumeAsync flow, the CLI now starts a Workflow run, reads a resumable NDJSON stream, dispatches local prompt/tool actions, posts hook results back to the API, and reconnects with startIndex when needed.

This intentionally does not preserve the old Mastra client contract.

Why

• match the backend rewrite in cli-init-api
• simplify the init transport to a durable workflow run plus streamed events
• keep local side effects in the CLI while letting the backend own workflow state and progress
• remove the need to upload eager file caches / directory listings as workflow inputs

What Changed

• replaces the old init transport with:
  • POST /api/init
  • GET /api/init/:runId/stream
  • POST /api/init/actions/:actionId
• adds NDJSON event parsing and resumable stream reconnect support via startIndex
• deduplicates replayed action_request events so reconnects do not rerun local mutations
• keeps local prompts, file edits, command execution, and Sentry auth/project work on the CLI side
• removes authToken, dirListing, and fileCache from the initial workflow payload
• updates spinner/rendering logic for the new structured event stream
• removes the old MASTRA_API_URL fallback and uses the new init transport directly
• adds transport-focused tests for start, reconnect, action resume, and NDJSON parsing

Paired Change

Paired API PR: getsentry/cli-init-api#100

These two PRs are a pair.

• Do not merge or release this CLI PR without the paired API PR.
• Prefer landing these together.
• If deployment sequencing is unavoidable, deploy the API PR first and only then merge/release this CLI PR.

How To Run Locally

Check out this PR and the paired API PR together.

1. Start the API from the paired cli-init-api checkout:

   cd /path/to/cli-init-api/apps/server
   bun run dev

2. In the target app shell, point the CLI at the local API:

   export INIT_API_URL=http://localhost:3000

3. Run sentry init from this checkout:

   cd /path/to/target-app
   bun run /path/to/cli/src/bin.ts init

Verification

• bun test test/lib/init/transport.test.ts test/lib/init/wizard-runner.test.ts test/commands/init.test.ts
• bun run typecheck
• local dry-run and real-run against the Next.js fixture with the paired API PR

Notes

• This PR intentionally assumes the new API contract and is not meant to ship before the paired backend rewrite.

[github-actions]

Semver Impact of This PR

🟡 Minor (new features)

📋 Changelog Preview

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Entries from this PR are highlighted with a left border (blockquote style).

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New Features ✨

• (init) Rewrite init CLI transport for Vercel Workflows by betegon in #779

• (issue) Add resolve, unresolve (reopen), and merge commands by BYK in #778

Bug Fixes 🐛

Init

• Use isatty(0) for TTY detection and add diagnostic probe by BYK in #767
• Reuse detected existing project data by betegon in #766
• Ensure project reuse and spinner states by MathurAditya724 in #763

Other

• (arg-parsing) Accept underscores in Sentry slugs (Slug normalization breaks projects with underscores in their slug #770) by BYK in #771
• (ci) Scope build-binary and build-docs to production environment by BYK in #773
• (dsn) Limit concurrent stat() calls in project root detection (CLI-19A) by BYK in #768
• (error-reporting) Fall back to message prefix for ValidationError without field by BYK in #776
• (hex-id) Auto-recover malformed hex IDs in view commands (CLI-16G) by BYK in #777
• (project-create) Preserve ApiError type so 4xx errors are silenced by BYK in #775
• (resolve-target) Reference original input in fuzzy-recovery warnings (enhancement(arg-parsing): fallback to original slug when space-normalization fails resolution #772) by BYK in #774
• (telemetry) Reduce Sentry issue fragmentation with stable fingerprinting by BYK in #769

Internal Changes 🔧

• Regenerate docs by github-actions[bot] in 58a84035
• Regenerate docs by github-actions[bot] in b0243668
• Regenerate docs by github-actions[bot] in e02799c1

Other

• release: 0.28.1 by BYK in 5c8df3f8

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