feat: add public one-line remote installer for DeepSQL (#118)

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## Summary

Adds a `remote-install.sh` script for one-liner DeepSQL self-host
installation:

```bash
curl -fsSL https://raw.githubusercontent.com/DeepSQLAI/deepsql/main/scripts/self-host/remote-install.sh | bash
```

## Features

- **Platform detection**: Linux (amd64/arm64) and macOS support
- **Prerequisite checks**: Validates bash, curl, git, Docker, Compose
v2, and buildx
- **Auto-versioning**: Fetches latest release tag from GitHub API, falls
back to `main`
- **Shallow clone**: Uses `--depth 1` for fast cloning
- **Environment setup**: Creates `.env` from template
- **Optional auto-install**: `--yes` flag for noninteractive mode
- **Remote-friendly guidance**: Pre-clone Docker/buildx messages use
`raw.githubusercontent.com` URLs

## Options

| Flag | Description |
|------|-------------|
| `-y, --yes` | Run `install.sh` automatically after setup |
| `--skip-docker-check` | Skip Docker/Compose/buildx verification |
| `--branch <ref>` | Use specific branch or tag instead of latest
release |

## Environment Variables

| Variable | Default | Description |
|----------|---------|-------------|
| `DEEPSQL_HOME` | `$HOME/deepsql` | Installation directory |
| `DEEPSQL_BRANCH` | (latest release) | Branch or tag to checkout |

## Security

- Downloads only from GitHub (`raw.githubusercontent.com`, `github.com`,
`api.github.com`)
- No third-party binaries — everything builds from source
- Transparent: users can inspect the script before running

## Follow-up Fix (latest commit)

- **Bug fixed**: `check_docker()` previously printed `sudo
./scripts/self-host/bootstrap-server.sh` when Docker was missing on
Linux, but that path doesn't exist until after `clone_or_update` runs
- **Solution**: Changed to remote one-liner: `curl -fsSL
https://raw.githubusercontent.com/.../bootstrap-server.sh | sudo bash`
- **Also fixed**: Same issue in buildx-missing guidance
- **Hardened**: `get_latest_release_tag()` now explicitly:
  - Matches only `^v[0-9]` product tags (e.g., `v1.3.0`)
  - Excludes `desktop-v*` and other prefixed tags
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---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>

Author: venkateshsakamuri-lab

README.md

@@ -23,6 +23,18 @@ DeepSQL Desktop first ship + Agent/Brain/Editor hardening. Notes:
 
 ## Quick start
 
+### One-liner install
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/DeepSQLAI/deepsql/main/scripts/self-host/remote-install.sh | bash
+```
+
+This checks prerequisites, clones the latest release to `~/deepsql`, and guides you
+through configuration. See [`scripts/self-host/remote-install.sh`](scripts/self-host/remote-install.sh)
+for options (`--yes` for noninteractive, `--branch` for a specific version).
+
+### Step-by-step
+
 Five steps, in order. Budget about fifteen minutes, most of it waiting on the first build.
 
 ### 1. Check you have what you need