fix(amplitude-session) + feat: prerelease channels - recover lastEventTime & implement branch-specific releases

[abueide]

Summary

This PR includes two sets of changes:

1. Fix 0-second sessions in Amplitude Session plugin on iOS when Background Fetch is enabled
2. Implement branch-specific prerelease channels for better semantic versioning

---

Part 1: Amplitude Session Fix

Changes

• Add recovery logic in startNewSessionIfNecessary() for partial AsyncStorage persistence
• Recover lastEventTime from sessionId when lastEventTime === -1 but sessionId >= 0
• Remove lastEventTime === -1 from isSessionExpired check (now handled by recovery)
• Remove incorrect 1-second timestamp guard from onForeground()
• Add 8 hypothesis-driven tests for 0-second session reproduction

Why

Plugin persists sessionId and lastEventTime via independent fire-and-forget writes. If app is killed before all writes complete (common during iOS Background Fetch), sessionId may persist while lastEventTime doesn't. On next launch, lastEventTime === -1 with valid sessionId falsely triggers session expiration, ending the just-created session immediately.

---

Part 2: Branch-Specific Prerelease Channels

Changes

1. Updated release.config.js:

branches: [
  'master',
  { name: '+([0-9])?(.{+([0-9]),x}).x', prerelease: true },
  { name: 'beta', prerelease: 'beta' },      // explicit beta channel
  { name: 'fix/*', prerelease: 'fix' },      // bug fixes → x.x.x-fix.N
  { name: 'feat/*', prerelease: 'feat' },    // features → x.x.x-feat.N
]

Before: All non-master branches published as x.x.x-beta.N
After: Each branch type gets its own channel and dist-tag

Examples:

• fix/ios-zero-second-sessions → 2.22.1-fix.1 (dist-tag: fix)
• feat/new-analytics → 2.22.1-feat.1 (dist-tag: feat)
• beta → 2.22.1-beta.1 (dist-tag: beta)

2. GitHub Environment:

• Created new Publish-Prerelease environment
• Updated workflow to use Publish-Prerelease instead of Publish-Beta

3. Workflow Input Clarity:

Renamed workflow input from beta to prerelease:

inputs:
  type:
    options:
      - dry-run
      - prerelease    # was: beta
      - production

4. Documentation:

Added PRERELEASE_SETUP.md with complete setup and troubleshooting guide.

Benefits

1. Semantic Clarity: x.x.x-fix.1 is clearer than x.x.x-beta.1 for a bug fix
2. Multiple Channels: Can distribute fixes and features independently
3. Better Client Experience: Clients can install specific channels:

   npm install @segment/analytics-react-native@fix
   npm install @segment/analytics-react-native@feat

4. No Breaking Changes: Existing beta channel still works

Testing

After merge, the workflow will show the new prerelease option. To test:

# Dry run
gh workflow run release.yml -f type=dry-run --ref fix/your-branch

# Publish
gh workflow run release.yml -f type=prerelease --ref fix/your-branch

No npm-side setup needed - we already use npm OIDC with provenance.

---

🤖 Generated with Claude Code