feat: consolidate marketplace skills into kyberforge plugin

Moves create-plugin, marketplace-architect, write-skill, and write-eval
from canonical .agents/skills/ into plugins/kyberforge/skills/, along
with all bundled sub-files, evals, and the plugin-marketplace-architecture
research doc. Bundles templates/plugin/ into create-plugin/assets/plugin-template/
so the skill is self-contained after install-time caching. Removes
templates/plugin/ and docs/research/plugin-marketplace-architecture.md
from the repo root as they are now exclusively in the plugin.

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

plugins/kyberforge/skills/marketplace-architect/references/cross-compat.md

@@ -0,0 +1,79 @@
+# Cross-Tool Compatibility Reference
+
+Claude Code and GitHub Copilot CLI share the plugin concept but diverge in specific, breaking
+ways. **Skills are the portable core. Manifests and agents are where they split.**
+
+Make Claude Code the source of truth — it is the stricter, more fully specified format.
+Treat "loads in Copilot CLI" as a tested checklist item per plugin, not an assumption.
+
+---
+
+## Divergence table
+
+| Concern | Claude Code | GitHub Copilot CLI | Portable choice |
+|---|---|---|---|
+| Marketplace manifest path | `.claude-plugin/marketplace.json` (required) | `.github/plugin/marketplace.json` (primary); also reads `.claude-plugin/` | Put it in `.claude-plugin/` — both read it. Optionally mirror to `.github/plugin/`. |
+| Plugin manifest path | `.claude-plugin/plugin.json` (required; only `plugin.json` goes in this dir) | `plugin.json` at **plugin root** | Ship in both locations until verified — see ⚠️ below |
+| Skills | `skills/<name>/SKILL.md` | `skills/<name>/SKILL.md` | ✅ Identical |
+| Agents | `agents/<name>.md` | `agents/<name>.agent.md` (frontmatter incl. `tools:`) | Diverges — keep portable logic in skills; ship per-tool agent files only when needed |
+| Hooks | `hooks/hooks.json` | `hooks.json` at plugin root | Diverges; declare paths in manifest to be safe |
+| MCP servers | `.mcp.json` at plugin root | `.mcp.json` at plugin root | ✅ Same |
+| Relative `source` | must start with `./` | `./x` and `x` both valid | Always use `./` — valid for both |
+| Validate command | `claude plugin validate .` (or `/plugin validate .`) | none documented | Run Claude validator + manual JSON checks for Copilot |
+| Install marketplace | `claude plugin marketplace add owner/repo` | `copilot plugin marketplace add owner/repo` | Same shape |
+| Install plugin | `claude plugin install <name>@<marketplace-name>` | install by plugin name; `@marketplace` suffix unconfirmed | ⚠️ Verify Copilot install string before documenting |
+| Local install (dev) | `claude --plugin-dir ./plugin` | `copilot plugin install ./plugin` | Tool-specific |
+| Component paths in plugin.json | Claude defaults to standard dirs; path overrides via marketplace entry only | `"skills": "skills/"`, `"agents": "agents/"`, etc. in plugin.json | Generate per-tool manifests rather than one shared file |
+
+> ⚠️ **UNVERIFIED — test before committing to a layout.**
+> Copilot docs confirm it reads the **marketplace** manifest from `.claude-plugin/`. They do NOT
+> confirm the same fallback for a plugin's `plugin.json`. Copilot docs show `plugin.json` at plugin
+> root; Claude requires it in `.claude-plugin/`. Until verified: ship `plugin.json` in BOTH
+> `plugin-name/plugin.json` and `plugin-name/.claude-plugin/plugin.json` (identical content), then
+> drop whichever proves redundant.
+
+---
+
+## `@<marketplace-name>` resolution
+
+`claude plugin install startup-cto@my-ai-marketplace` requires the marketplace manifest's
+top-level `name` field to be exactly `my-ai-marketplace`. It is **not** the GitHub repo name.
+Keep them aligned to avoid confusion, but they are separate fields.
+
+---
+
+## Canonical cross-compatible repo layout
+
+```text
+repo-root/
+├── .claude-plugin/
+│   └── marketplace.json          # both tools read here
+├── .github/plugin/
+│   └── marketplace.json          # OPTIONAL: Copilot canonical path (mirror)
+├── plugins/
+│   └── startup-cto/
+│       ├── plugin.json           # Copilot root manifest  ┐ ship both until
+│       ├── .claude-plugin/       #                        │ the note above is
+│       │   └── plugin.json       # Claude manifest        ┘ verified
+│       ├── skills/
+│       │   ├── fundraising/SKILL.md
+│       │   └── hiring/SKILL.md
+│       ├── agents/
+│       │   ├── startup-cto.md        # Claude
+│       │   └── startup-cto.agent.md  # Copilot (only if shipping native agents)
+│       ├── hooks/hooks.json          # Claude
+│       ├── hooks.json                # Copilot (if hooks used)
+│       └── README.md
+└── README.md
+```
+
+---
+
+## Open questions to resolve before generating layouts
+
+1. **Does Copilot CLI load a plugin whose `plugin.json` lives only in `.claude-plugin/`?**
+   Install a test plugin both ways. The answer decides whether to ship one manifest or two.
+
+2. **What is Copilot's exact install-from-marketplace command?**
+   Run `copilot plugin install --help`. The `update`/`uninstall` commands take a bare plugin
+   name — the `@marketplace` form may not apply.