Add os-alt (a directory of self-hostable open-source alternatives, similar to alternativeto)

**Add proprietary tool: os-alt**

A directory of paid SaaS products mapped to **strictly self-hostable** open-source alternatives. Similar in shape to your existing [/alternatives/alternativeto](https://opensource.builders/alternatives/alternativeto) entry — i.e. a "directory of alternatives" that itself has open-source peers.

- **Description:** Curated index of 50 SaaS products (Notion, Slack, Linear, Datadog, Auth0, AWS S3, Mailchimp, Linktree, …) where each page lists 2–5 open-source alternatives plus four data points the SaaS-discovery competitors don't surface: setup-time score (`easy / moderate / hard`), monthly self-host cost on a small VPS, a one-paragraph migration sketch from the SaaS to the OSS tool, and a per-alternative health pill (`alive / stale / dead` from GitHub last-commit + archived flag).
- **Website:** https://code-rho-dun.vercel.app/ (custom domain pending; the Vercel URL is the canonical production URL today)
- **Category:** Software discovery / OSS alternative directory (same bucket as your `alternativeto` entry)
- **Features:**
- Strict self-hostability filter (excludes "OSS but service-only" and crippled self-host editions)
- Setup-time + monthly-cost estimate per alternative
- Concrete export-from-SaaS / import-to-OSS migration sketches
- Live freshness indicator (alive / stale / dead) refreshed daily via GitHub API
- Built-in `WebPage + ItemList + BreadcrumbList` JSON-LD on every page; sitemap + robots; IndexNow-pinged
- 50 SaaS pages live as of submission date; pipeline to scale to 100+

**Suggested OSS alternatives to list against this entry** (in the same way `alternativeto` lists `openalternative.co` etc.):
- [openalternative.co](https://openalternative.co/) — GitHub-stars-driven OSS alternative directory
- [awesome-selfhosted](https://github.com/awesome-selfhosted/awesome-selfhosted) — canonical curated list of self-hostable software
- [opensourcealternative.to](https://www.opensourcealternative.to/) — another peer directory (no recent commits — listing-as-stale candidate)

**Source visibility:** The site source is currently in a private repo while the editorial pipeline stabilizes; happy to discuss publishing it if listing requires it. The data layer (per-SaaS JSON files, GitHub-API-driven freshness) is reproducible from the live site if you want to cross-check our health flags vs. yours.

Happy to adjust the entry to whatever schema fits your dataset best — let me know.