feat(ga-agent): Add GA Agent project with decomposed architecture

Create workspace for building Google Analytics Claude Skill with:
- 5 independent components (MCP setup, skill, dimension explorer, Slack reporter, realtime watcher)
- Comprehensive project plan and documentation
- Step-by-step setup guides for each component

Components:
1. MCP Setup - GA4 + BigQuery MCP server installation
2. GA Agent Skill - Core Claude Skill for interactive analysis
3. Dimension Explorer - Validate dims/metrics with explanations
4. Slack Reporter - Automated reports to Slack (P2)
5. Realtime Watcher - Real-time monitoring (deferred)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ga-agent-project/04-slack-reporter/README.md

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+# Component 4: Slack Reporter
+
+**Type:** Standalone Service
+**Priority:** P2
+**Status:** Not Started
+
+## Goal
+
+Automated GA4 reports delivered to Slack channels.
+
+## Features
+
+| Report | Schedule | Content |
+|--------|----------|---------|
+| Daily Summary | 9:00 AM | Users, sessions, top 5 pages |
+| Weekly Digest | Monday 9 AM | WoW comparison, trends |
+| Anomaly Alert | Real-time | Traffic ±30% from baseline |
+
+## Structure
+
+```
+04-slack-reporter/
+├── README.md
+├── config.yaml              # Configuration
+├── reporter.py              # Main service
+├── queries/
+│   ├── daily_summary.py
+│   ├── weekly_digest.py
+│   └── anomaly_check.py
+├── templates/
+│   └── slack_blocks.py      # Slack Block Kit
+├── requirements.txt
+├── Dockerfile
+└── docker-compose.yml
+```
+
+## Configuration
+
+### config.yaml
+
+```yaml
+slack:
+  bot_token: ${SLACK_BOT_TOKEN}
+  default_channel: "#analytics-reports"
+
+ga4:
+  property_id: "123456789"
+  credentials_path: "/path/to/credentials.json"
+
+reports:
+  daily_summary:
+    enabled: true
+    schedule: "0 9 * * *"  # 9 AM daily
+    channel: "#analytics-reports"
+
+  weekly_digest:
+    enabled: true
+    schedule: "0 9 * * 1"  # 9 AM Monday
+    channel: "#analytics-reports"
+
+  anomaly_alert:
+    enabled: true
+    check_interval: 3600  # Check every hour
+    threshold: 0.3        # 30% deviation
+    channel: "#analytics-alerts"
+```
+
+## Slack App Setup
+
+1. Go to [api.slack.com/apps](https://api.slack.com/apps)
+2. Create New App → From scratch
+3. Add OAuth scopes:
+   - `chat:write`
+   - `files:write`
+   - `channels:read`
+4. Install to workspace
+5. Copy Bot Token (`xoxb-...`)
+
+## Dependencies
+
+```
+# requirements.txt
+google-analytics-data>=0.18.0
+google-auth>=2.23.0
+slack-sdk>=3.23.0
+apscheduler>=3.10.0
+pandas>=2.0.0
+plotly>=5.18.0
+kaleido>=0.2.1
+pyyaml>=6.0
+```
+
+## Slack Message Format
+
+Using Block Kit for rich formatting:
+
+```python
+def daily_summary_blocks(data: dict) -> list:
+    return [
+        {
+            "type": "header",
+            "text": {"type": "plain_text", "text": "📊 Daily GA4 Summary"}
+        },
+        {
+            "type": "section",
+            "fields": [
+                {"type": "mrkdwn", "text": f"*Users:* {data['users']:,}"},
+                {"type": "mrkdwn", "text": f"*Sessions:* {data['sessions']:,}"},
+                {"type": "mrkdwn", "text": f"*Pageviews:* {data['pageviews']:,}"},
+                {"type": "mrkdwn", "text": f"*Bounce Rate:* {data['bounce_rate']:.1%}"},
+            ]
+        },
+        {"type": "divider"},
+        {
+            "type": "section",
+            "text": {"type": "mrkdwn", "text": "*Top Pages:*\n" + data['top_pages']}
+        }
+    ]
+```
+
+## Deployment
+
+### Local Development
+
+```bash
+# Install dependencies
+pip install -r requirements.txt
+
+# Set environment variables
+export SLACK_BOT_TOKEN=xoxb-...
+export GOOGLE_APPLICATION_CREDENTIALS=/path/to/creds.json
+
+# Run
+python reporter.py
+```
+
+### Docker
+
+```bash
+docker-compose up -d
+```
+
+### Cloud Options
+
+- Google Cloud Run (scheduled via Cloud Scheduler)
+- AWS Lambda + EventBridge
+- Railway / Render
+
+## Checklist
+
+- [ ] Slack App created
+- [ ] config.yaml template
+- [ ] daily_summary.py
+- [ ] weekly_digest.py
+- [ ] anomaly_check.py
+- [ ] slack_blocks.py templates
+- [ ] reporter.py scheduler
+- [ ] Dockerfile
+- [ ] Tested locally
+- [ ] Deployed