feat: add Gemini skill integration and multi-user AI setup

GEMINI.md

@@ -0,0 +1,52 @@
+# Gemini Project Contract
+
+This repository is **ServerManager** — a cross-platform desktop GUI for managing remote servers and services through one encrypted local inventory.
+
+Use this file as the native Gemini contract for sessions started inside this repository.
+
+## First Read
+
+Read these files first when relevant:
+
+- `README.md`
+- `CLAUDE.md`
+- `CHANGELOG.md`
+- `core/claude_setup.py`
+- `tools/ssh.py`
+
+## Default Role
+
+- Gemini is a secondary implementation and review helper, not the owner of the project state.
+- Prefer minimal safe changes that preserve Claude and Codex integration behavior.
+- When changing AI integration code, keep Claude `/ssh`, Codex `server-manager`, and Gemini `server-manager` behavior aligned.
+
+## Project-Specific Rules
+
+- Never read or print secrets from `~/.server-connections/servers.json`, `settings.json`, or `encryption.py`.
+- Treat `tools/ssh.py` as the shared transport layer for Claude, Codex, and Gemini.
+- Keep cross-platform behavior explicit for Linux, macOS, and Windows.
+- Prefer shared installer logic in `core/claude_setup.py` over duplicated per-tool logic.
+- If command semantics change in `tools/ssh.py`, update all relevant user-facing skill docs.
+
+## Native Gemini Entry Points
+
+- Project contract: `GEMINI.md`
+- Gemini settings: `.gemini/settings.json`
+- Workspace skill: `.gemini/skills/server-manager/`
+
+## Safe Server Workflow
+
+When the user asks to operate on a server already configured in ServerManager:
+
+1. Use the installed ServerManager Gemini skill.
+2. First enumerate aliases safely.
+3. Determine endpoint type before choosing a command.
+4. Use the shared CLI wrapper, not raw credentials.
+
+Preferred discovery commands:
+
+```bash
+$HOME/.server-connections/gemini-ssh --list
+$HOME/.server-connections/gemini-ssh --info ALIAS
+$HOME/.server-connections/gemini-ssh --status
+```