{Feature} Project Aria Plugins - Add Gemini CLI extension support

Summary:
Add Gemini CLI extension support to the `projectaria-plugins` marketplace, following the same pattern as the `superpowers` project. This enables Gemini CLI users to install and use ARK skills natively.

Changes:
- `gemini-extension.json` (new): Gemini CLI extension entry point, declares context file
- `GEMINI.md` (new, root): Context file loaded at session start, includes tool mapping table (Claude Code tool names → Gemini CLI equivalents) and `@./` imports for all 6 ARK skills
- `projectaria_ark_plugin/GEMINI.md` (fix): Corrected broken `import` paths to proper `@./skills/...` syntax, added tool mapping table
- `README.md`: Added Gemini CLI installation section alongside existing Claude Code and Codex instructions

Reviewed By: ryanfrawley, nrraina

Differential Revision: D106684288

fbshipit-source-id: 9c58925012442622471dbcd73f5bcdd7c6745d77

Author: kongchen1992

GEMINI.md

@@ -0,0 +1,27 @@
+# Aria ARK — Gemini CLI Context
+
+> **ARK** = Aria Research Kit — the developer toolset for Project Aria smart glasses.
+
+## Tool Mapping
+
+Skills use Claude Code tool names. When you encounter these in a skill, use your Gemini CLI equivalent:
+
+| Skill references | Gemini CLI equivalent |
+|-----------------|----------------------|
+| `Read` (file reading) | `read_file` |
+| `Write` (file creation) | `write_file` |
+| `Edit` (file editing) | `replace` |
+| `Bash` (run commands) | `run_shell_command` |
+| `Grep` (search file content) | `grep_search` |
+| `Glob` (search files by name) | `glob` |
+| `WebSearch` | `google_web_search` |
+| `WebFetch` | `web_fetch` |
+
+## Skills
+
+@./projectaria_ark_plugin/skills/projectaria-tools/SKILL.md
+@./projectaria_ark_plugin/skills/client-sdk/SKILL.md
+@./projectaria_ark_plugin/skills/mps/SKILL.md
+@./projectaria_ark_plugin/skills/vrs-health-check/SKILL.md
+@./projectaria_ark_plugin/skills/pilot-dataset/SKILL.md
+@./projectaria_ark_plugin/skills/web-app-creator/SKILL.md

README.md

@@ -39,6 +39,17 @@ codex plugin marketplace add https://github.com/facebookresearch/projectaria-plu
 Then open Codex chat, run `/plugin`, choose the Project Aria Plugins
 marketplace, and install any plugin from it, e.g.`aria-ark`.
 
+### Gemini CLI
+
+Install as a Gemini CLI extension:
+
+```bash
+gemini extensions install https://github.com/facebookresearch/projectaria-plugins.git
+```
+
+The extension loads the `GEMINI.md` context file at session start, which
+includes a tool mapping table and imports all ARK skill content.
+
 ## Plugins
 
 | Plugin | Description |

gemini-extension.json

@@ -0,0 +1,6 @@
+{
+  "name": "aria-ark",
+  "description": "Aria Research Kit (ARK) skills for building applications with Project Aria smart glasses",
+  "version": "1.0.0",
+  "contextFileName": "GEMINI.md"
+}

projectaria_ark_plugin/GEMINI.md

@@ -2,17 +2,26 @@
 
 > **ARK** = Aria Research Kit — the developer toolset for Project Aria smart glasses.
 
-## Data Processing (projectaria-tools)
-
-TODO
-
-## Real-Time Webapp Development (Aria Flow)
-
-TODO
-
-## Quick Reference
-
-TODO
-
-@import projectaria-ark-plugin/skills/aria-research-kit/SKILL.md
-@import projectaria-ark-plugin/skills/aria-flow/SKILL.md
+## Tool Mapping
+
+Skills use Claude Code tool names. When you encounter these in a skill, use your Gemini CLI equivalent:
+
+| Skill references | Gemini CLI equivalent |
+|-----------------|----------------------|
+| `Read` (file reading) | `read_file` |
+| `Write` (file creation) | `write_file` |
+| `Edit` (file editing) | `replace` |
+| `Bash` (run commands) | `run_shell_command` |
+| `Grep` (search file content) | `grep_search` |
+| `Glob` (search files by name) | `glob` |
+| `WebSearch` | `google_web_search` |
+| `WebFetch` | `web_fetch` |
+
+## Skills
+
+@./skills/projectaria-tools/SKILL.md
+@./skills/client-sdk/SKILL.md
+@./skills/mps/SKILL.md
+@./skills/vrs-health-check/SKILL.md
+@./skills/pilot-dataset/SKILL.md
+@./skills/web-app-creator/SKILL.md