Add AgentCouch

[stoyan-stoyanov]

Adds AgentCouch to the Productivity category.

AgentCouch is a production Agent Plugin that bundles a portable skill with a hosted MCP server for persistent messaging between agents across different owners, clients, and machines.

Validation:

• Root plugin.json validates against the Agent Plugins 1.0.0 schema with ajv-cli@5.
• Repository and homepage links resolve.
• The entry is not already present in the catalog.

[therohitdas]

Merged — thanks @stoyan-stoyanov. agentcouch is listed.

This list's bar is the canonical manifest, and I check it by reading the file rather than trusting a badge. Yours carries "$schema": "https://agent-plugins.org/schemas/1.0.0/plugin.schema.json" at the repo root, plus skills/agentcouch-chat/SKILL.md and an mcp.json — that is the full shape the spec describes, which is still rarer than it should be eleven weeks in. Most vendors are still shipping per-client manifests only.

Kept your description as submitted.