feat: add SparkToro as audience research tool

Add SparkToro integration guide, registry entry, and references in
customer-research skill. SparkToro reveals where your ICP spends time
using clickstream, search, and social data — essential for finding
podcasts, YouTube channels, subreddits, and websites your audience
engages with.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/REGISTRY.md

@@ -74,6 +74,7 @@ Quick reference for AI agents to discover tool capabilities and integration meth
 | pendo | Product Analytics | ✓ | - | [✓](clis/pendo.js) | - | [pendo.md](integrations/pendo.md) |
 | similarweb | Competitive Intelligence | ✓ | - | [✓](clis/similarweb.js) | - | [similarweb.md](integrations/similarweb.md) |
 | firehose | Competitive Intelligence | ✓ | - | - | - | [firehose.md](integrations/firehose.md) |
+| sparktoro | Audience Research | - | - | - | - | [sparktoro.md](integrations/sparktoro.md) |
 | airops | AI Content | ✓ | - | [✓](clis/airops.js) | - | [airops.md](integrations/airops.md) |
 | buffer | Social | ✓ | - | [✓](clis/buffer.js) | - | [buffer.md](integrations/buffer.md) |
 | wistia | Video | ✓ | - | [✓](clis/wistia.js) | - | [wistia.md](integrations/wistia.md) |
@@ -340,6 +341,16 @@ Traffic analytics, competitor benchmarking, and market research.
 
 **Agent recommendation**: Similarweb for competitor traffic analysis and market benchmarking.
 
+### Audience Research
+
+Audience intelligence and behavioral research tools.
+
+| Tool | Best For | Notes |
+|------|----------|-------|
+| **sparktoro** | Audience affinities, behavioral data | Clickstream + social data |
+
+**Agent recommendation**: SparkToro for discovering where your ICP spends time — what they read, watch, listen to, follow, and search for. Essential for customer research, content strategy, and media buying decisions.
+
 ### AI Content
 
 AI-powered content generation and optimization platforms.