fix(docs): update assistants index page for v2 schema sections

Update summary table with corrected hook event counts and replace
plugin model bullet with component paths, extension model, and
roadmap sections matching the new adoption spec structure.

Author: zircote

src/content/docs/assistants/index.mdx

@@ -0,0 +1,40 @@
+---
+title: "Assistants"
+description: "AI coding assistant adoption specifications for ccpkg cross-tool portability."
+---
+
+# Assistant Adoption Specifications
+
+ccpkg achieves cross-tool portability through a three-layer specification system:
+
+1. **Core Specification** — Defines the universal packaging format, manifest schema, component types, and lifecycle operations. Tool-agnostic by design.
+
+2. **[Adoption Meta-Specification](/specification/overview#relationship-to-assistant-adoption-specifications)** — Defines the contract for what an adoption spec must contain: identity fields, component support levels, hook event mappings, MCP integration details, and adapter operations.
+
+3. **Individual Adoption Specs** — One JSON file per assistant, declaring exactly how that assistant integrates with ccpkg. Machine-validated against a JSON Schema.
+
+## Reading an Adoption Spec
+
+Each assistant page below documents:
+
+- **Component Support** — Which ccpkg component types the assistant supports natively, via adapter, experimentally, or not at all.
+- **Instructions** — The filename and format the assistant uses for instruction injection.
+- **Hook Events** — How ccpkg canonical event names map to the assistant's native hook events, plus any host-specific events.
+- **MCP Integration** — Transport support, credential prefix, and configuration locations.
+- **Component Paths** — Where each component type is installed at user and project scope.
+- **Extension Model** — How the assistant discovers and loads extensions (bundle vs scatter).
+- **Roadmap** — Planned or in-progress changes to the assistant's ccpkg support.
+
+## Contributing
+
+To add support for a new assistant, create a JSON file in `spec/assistants/` following the [adoption specification format](/specification/overview#relationship-to-assistant-adoption-specifications). See the [Contributing Guide](https://github.com/zircote/ccpkg/blob/main/CONTRIBUTING.md) for details.
+
+## Supported Assistants
+
+| Assistant | Vendor | Instructions File | Hook Events | MCP |
+|---|---|---|---|---|
+| [Claude Code](/assistants/claude-code) | Anthropic | `CLAUDE.md` | 7 canonical + 10 host-specific | Native |
+| [Copilot CLI](/assistants/copilot-cli) | GitHub | `.github/copilot-instructions.md` | 6 canonical | Native |
+| [Codex CLI](/assistants/codex-cli) | OpenAI | `AGENTS.md` | 1 canonical + 1 host-specific | Native |
+| [Gemini CLI](/assistants/gemini-cli) | Google | `GEMINI.md` | 6 canonical + 5 host-specific | Native |
+| [OpenCode](/assistants/opencode) | sst | `AGENTS.md` | 4 canonical + 9 host-specific | Native |