feat: v9.0.0 — three new agent templates (Discovery, Stakeholder Comms, Launch)

This release adds three new agent templates to the library, bringing the total to four.

New templates:
- PM Discovery Agent: synthesises customer interviews from Notion or Google Drive,
  identifies cross-interview themes, scores assumption confidence, generates follow-up questions
- PM Stakeholder Comms Agent: detects audience type (executive/investor/stakeholder/board),
  pulls activity from Linear/Jira/Drive, drafts in audience-appropriate format
- PM Launch Agent: end-to-end launch coordination with channel-specific content,
  calendar, success metrics, and launch checklist

Each template follows the established pattern: README, AGENT.md, orchestrate.sh,
2 subagents, connectors with example configs, examples, smoke test.

Total file count: 37 new files across 3 templates.

Updated README to position library as 4-template collection.
Bumped marketplace.json from v8.0.0 to v9.0.0.

templates/pm-stakeholder-comms-agent/connectors/linear.example.json

@@ -0,0 +1,50 @@
+{
+  "connector_name": "linear",
+  "version": "1.0.0",
+  "description": "Linear connector for the PM Stakeholder Communications Agent. Provides access to recently shipped issues and current sprint progress for inclusion in stakeholder updates.",
+  
+  "configuration": {
+    "workspace_url": "https://linear.app/your-workspace-name",
+    "team_id": "TEAM_ID_HERE",
+    "default_period_filter": "last_30_days",
+    "include_closed_issues": true,
+    "include_in_progress_issues": true,
+    "exclude_label": "internal-only",
+    "rate_limit_requests_per_minute": 60
+  },
+  
+  "credentials": {
+    "api_key_env_var": "LINEAR_API_KEY",
+    "api_key_placeholder": "lin_api_xxxxxxxxxxxxxxxxxxxxxxxx"
+  },
+  
+  "available_operations": [
+    {
+      "name": "list_recently_shipped",
+      "description": "Get all issues completed in the specified period",
+      "filters": ["completed_after", "completed_before", "team_id", "project", "label", "exclude_label"],
+      "max_results": 100
+    },
+    {
+      "name": "list_in_progress",
+      "description": "Get current in-progress and ready issues for context on what's coming next",
+      "filters": ["team_id", "project", "label"]
+    },
+    {
+      "name": "get_issue_summary",
+      "description": "Get a brief summary of a specific issue for inclusion in updates",
+      "required_input": "issue_id"
+    }
+  ],
+  
+  "_setup_instructions": [
+    "1. Generate a Linear API key at https://linear.app/settings/account/security",
+    "2. Set LINEAR_API_KEY environment variable",
+    "3. Find your team ID (see linear.example.json in pm-sprint-agent template for command)",
+    "4. Update team_id and workspace_url in this file",
+    "5. Save as 'linear.json'",
+    "6. Test: bash orchestrate.sh --audience executive --period 'last 30 days' --dry-run"
+  ],
+  
+  "_note_on_internal_only_label": "The exclude_label 'internal-only' lets you tag tickets that should not appear in any external communications. Useful for sensitive work or items not ready to communicate externally."
+}