Add roundup plugin: self-configuring status briefing generator (#1157)

* Add roundup plugin: self-configuring status briefing generator

Adds a new plugin with two skills:

- roundup-setup: Interactive onboarding that learns the user's communication
  style from examples, discovers available data sources, and builds audience
  profiles. Writes a persistent config to ~/.config/roundup/config.md.

- roundup: Generates draft status briefings on demand by pulling from
  configured sources (GitHub, M365, Slack, Google Workspace, etc.) and
  synthesizing in the user's learned style for any defined audience.

Platform-agnostic by design -- adapts to whatever MCP tools are available
in the user's environment rather than assuming specific integrations.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address PR review comments

- Fix 'use roundup' help text to clarify multi-audience behavior instead
  of referencing a nonexistent 'default audience'
- Split bundled 'who do you report to + who is on your team' into two
  separate ask_user questions per the one-question-at-a-time rule
- Specify ~/Desktop as explicit save path with fallback prompt when
  directory doesn't exist
- Tables in README verified as correct markdown (single | delimiters)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Improve example-pasting UX in setup flow

- Make 'paste the whole thing right here' explicit so users aren't
  unsure about what/how much to paste
- Confirm receipt more clearly ('grabbed all of that')
- Reframe second example prompt to explain why a second helps
- Cap follow-up asks at two so it doesn't feel nagging
- Note that messy formatting is fine

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Reinforce that more examples = better output

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/plugin/marketplace.json

@@ -435,6 +435,12 @@
       "description": "Complete toolkit for building Model Context Protocol (MCP) servers in Python using the official SDK with FastMCP. Includes instructions for best practices, a prompt for generating servers, and an expert chat mode for guidance.",
       "version": "1.0.0"
     },
+    {
+      "name": "roundup",
+      "source": "roundup",
+      "description": "Self-configuring status briefing generator. Learns your communication style from examples, discovers your data sources, and produces draft updates for any audience on demand.",
+      "version": "1.0.0"
+    },
     {
       "name": "ruby-mcp-development",
       "source": "ruby-mcp-development",