refactor: Deprecate tail command in favor of peek --follow

[szymdzum]

Summary

The tail command can be consolidated into peek --follow by adding a single missing feature: --interval. This would simplify the codebase and provide a more consistent API.

Current State

Feature	tail	peek --follow
Live updates	✅	✅
Custom interval	✅ --interval <ms>	❌ Hardcoded 1000ms
Network filter	✅ --network	✅ --network
Console filter	✅ --console	✅ --console
DOM filter	❌	✅ --dom
Type filter	❌	✅ --type

Key difference: tail allows --interval 100 to --interval 60000 for custom update frequency.

Proposed Changes

Phase 1: Add --interval to peek --follow

// In peek.ts
.option('--interval <ms>', 'Update interval in milliseconds (only with --follow)', '1000')

Validation: 100ms min, 60000ms max (same as tail)

Phase 2: Deprecate tail with warning

$ bdg tail
⚠️ Deprecation: "bdg tail" is deprecated. Use "bdg peek --follow" instead.
# Continue working normally

Phase 3: Remove tail (next major version)

Remove tail.ts entirely. Users have had warning period.

Benefits

1. Simpler codebase - Remove ~130 lines of duplicate logic in tail.ts
2. Consistent patterns - peek uses runCommand, tail doesn't
3. Better discoverability - One command with options vs two similar commands
4. Feature parity - peek --follow gains --interval, users get --dom and --type filters they didn't have with tail

Migration Path

# Before
bdg tail --interval 500 --network

# After  
bdg peek --follow --interval 500 --network

Checklist

• Add --interval <ms> option to peek command (only active with --follow)
• Update setupFollowMode to accept interval parameter
• Add deprecation warning to tail command
• Update documentation (CLI_REFERENCE.md, CLAUDE.md)
• Update task mappings to point to peek --follow
• Remove tail in next major version

Labels

• refactor
• enhancement
• good first issue (Phase 1 only)