Add Lead Scoring ML + Email Sequences/Drip Campaigns

Lead Scoring:
- lead_scoring_config table with configurable feature weights
- Scoring engine: boolean, keyword, and range-based feature scoring
- Settings tab: configure scoring features, run scoring on all leads
- ml_score + ml_score_details columns on leads table
- API: /api/leads/score, /api/leads/score/config
- mlScore returned in lead detail and list APIs

Email Campaigns:
- email_campaigns, email_campaign_steps, subscribers, logs tables
- Campaign list page with status badges and subscriber counts
- Campaign detail with step management, subscriber search/add, send
- Drip logic: steps with configurable delay days, template variables
- Variable replacement ({{name}}, {{email}}) in email bodies
- Sidebar: Campaigns nav item

database/migrations/026_email_campaigns.sql

@@ -0,0 +1,62 @@
+-- ============================================================================
+-- Email Sequences / Drip Campaigns — Automated follow-up sequences
+-- ============================================================================
+
+CREATE TABLE IF NOT EXISTS email_campaigns (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    name VARCHAR(255) NOT NULL,
+    description TEXT,
+    status VARCHAR(50) NOT NULL DEFAULT 'draft',
+    trigger_type VARCHAR(50) NOT NULL DEFAULT 'manual',
+    trigger_config JSONB,
+    created_by UUID REFERENCES users(id),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    deleted_at TIMESTAMPTZ
+);
+
+CREATE TABLE IF NOT EXISTS email_campaign_steps (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    campaign_id UUID NOT NULL REFERENCES email_campaigns(id) ON DELETE CASCADE,
+    step_order INT NOT NULL DEFAULT 0,
+    delay_days INT NOT NULL DEFAULT 0,
+    subject VARCHAR(500) NOT NULL,
+    body_text TEXT,
+    body_html TEXT,
+    variables JSONB,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS email_campaign_subscribers (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    campaign_id UUID NOT NULL REFERENCES email_campaigns(id) ON DELETE CASCADE,
+    lead_id UUID REFERENCES leads(id) ON DELETE SET NULL,
+    email VARCHAR(255) NOT NULL,
+    contact_name VARCHAR(255),
+    subscribed_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    unsubscribed_at TIMESTAMPTZ,
+    status VARCHAR(50) NOT NULL DEFAULT 'pending',
+    current_step INT NOT NULL DEFAULT 0,
+    last_sent_at TIMESTAMPTZ,
+    CONSTRAINT uq_campaign_lead UNIQUE (campaign_id, lead_id)
+);
+
+CREATE TABLE IF NOT EXISTS email_campaign_logs (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    campaign_id UUID REFERENCES email_campaigns(id) ON DELETE CASCADE,
+    subscriber_id UUID REFERENCES email_campaign_subscribers(id) ON DELETE CASCADE,
+    step_id UUID REFERENCES email_campaign_steps(id) ON DELETE SET NULL,
+    recipient VARCHAR(255) NOT NULL,
+    subject VARCHAR(500),
+    body_text TEXT,
+    sent_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    status VARCHAR(50) NOT NULL DEFAULT 'sent',
+    error_message TEXT
+);
+
+ALTER TABLE email_campaign_subscribers ADD CONSTRAINT IF NOT EXISTS uq_campaign_lead UNIQUE (campaign_id, lead_id);
+
+CREATE INDEX idx_campaign_steps_order ON email_campaign_steps(campaign_id, step_order);
+CREATE INDEX idx_campaign_subscribers ON email_campaign_subscribers(campaign_id, status);
+CREATE INDEX idx_campaign_logs ON email_campaign_logs(campaign_id, sent_at);