feat(seo): implement SEO-friendly report URLs, SSR, and dynamic sitemap

[igor-soldev]

This Pull Request introduces a comprehensive SEO overhaul for InfraScan reports. Previously, reports were served strictly as a Single Page Application (SPA) under query parameters (/?scan_id=<uuid>), which prevented search engines from properly crawling and indexing the valuable content within public scans.

This update transitions reports to dedicated, semantic URLs, implements Server-Side Rendering (SSR) specifically tailored for web crawlers, and introduces rich metadata without breaking any existing shared links.

Key Features & Changes

1. SEO-Friendly & Semantic URLs

• Introduced a new dedicated endpoint @app.route('/report/<path:scan_id>').
• URLs now dynamically include the sanitized repository name alongside the UUID (e.g., /report/github-soldevelo-infrascan-7a58c6a3...), which increases keyword saturation and organic discoverability.
• Updated frontend (app.js) to generate these semantic URLs for the "Share Results" functionality and within the "Recent Scans" history list.

2. Bulletproof Backward Compatibility

• Existing links using /?scan_id=<uuid> are fully supported. The index route acts as an interceptor that reads the scan metadata, resolves the repository name, and performs a native HTTP 301 Moved Permanently redirect to the new canonical URL. No user or existing external link is left behind.

3. Server-Side Rendering (SSR) for Crawlers

• Created a new templates/report.html (inheriting UI from index).
• Implemented a <noscript> block inside the #results-content container. This block natively renders the entire report schema (Repository Name, Overall Grades, Cost/Security Findings, and Recommendations) in pure HTML.
• Googlebot and other crawlers can now extract the full value of the report immediately upon requesting the page, while normal users will seamlessly transition into the interactive JS-powered SPA view.

4. Rich Meta Tags & Structured Data

• Dynamically injected <title>, <meta name="description">, OpenGraph (og:*), and Twitter Card meta tags into report.html using the report's metadata.
• Implemented <link rel="canonical" href="..."> pointing directly to the SEO-friendly URL to prevent any duplicate content penalties.
• Added application/ld+json Schema.org Structured Data (TechArticle and Review) to enable Google Rich Results.

5. Dynamic XML Sitemap

• Removed the static sitemap.xml file.
• Introduced a dynamic @app.route('/sitemap.xml') endpoint that yields canonical links to all stored public reports, allowing search engines to discover reports easily.

6. UX Improvements

• Adjusted frontend logic to ensure UI elements (Tabs, Share Button) render correctly when visiting the new /report/ routes.
• Clicking the "New Scan" button while viewing a dedicated report will now cleanly redirect the user back to the homepage (/) to begin a new scan flow.

🧪 Testing

• Backward Compatibility: Visiting /?scan_id=<existing-uuid> properly redirects (301) to the new structure.
• SSR Validation: Disabling JavaScript in the browser still displays the full textual report via the <noscript> tag.
• Sitemap Generation: /sitemap.xml successfully lists all available non-private scans.
• UI Interaction: Standalone report URLs natively display the results, and the "Share Results" feature copies the correct /report/repo-uuid path.