feat: Twitter Automation and Engagement System

[zp6]

Summary

Implements the complete Twitter Automation and Engagement system as specified in #61.

Features Implemented

Scheduling System

• ScheduleTweet prism: Schedule tweets with timezone awareness, queue management, and 30-day advance limit
• ContentCalendar prism: Full content calendar with add/update/remove/list/schedule operations, campaign grouping, and tag support

Rule-Based Engagement System

• EngagementRulesEngine prism: Configurable rules engine with conditions (equals, contains, regex, gt, lt, in) and actions (reply, like, retweet, follow, dm)
• AutoReply prism: Pattern-matching auto-reply with contains/regex/exact/starts_with modes, conditions (min followers, sentiment, language), and rate limiting

Content Management System

• ContentCurator prism: Multi-source content discovery (RSS, API, hashtag, user timeline) with engagement scoring, filtering, and tweet suggestions
• Source management (add/remove/list sources)

Queue Management

• ETS-based scheduling queues with configurable queue names
• Position tracking and queue state management

Follow/Unfollow Management

• FollowManager prism: Auto-follow-back, unfollower pruning, engagement-based filtering (min followers, max following)
• Dry-run mode for safe testing

DM Automation

• DMAutomation prism: Send DMs, welcome messages with quick replies, conversation listing and history

Orchestration Beam

• TwitterAutomationBeam: Combines content curation, rule evaluation, scheduling, and follow-back in a unified workflow

Integration Client

• Twitter Client: OAuth 2.0 bearer token auth, rate limit handling with reset tracking, media upload support

Architecture

Follows lux prism/beam patterns:

• 7 prisms under Lux.Prisms.Twitter.{Automation,Engagement}
• 1 beam: Lux.Beams.Twitter.TwitterAutomationBeam
• Integration client: Lux.Integrations.Twitter.Client
• 1,774 lines of idiomatic Elixir code

Closes #61