[DOCS] Overhaul new-user onboarding, home page, and upload flow (#2347)

Getting started:
- New 15-minute Getting Started guide featuring the two most popular
  tracks (BLE on esp32dev-ble, RF on lilygo-rtl_433), with broker setup
  and a verification step
- Sidebar restructured around the new-user journey; upload options
  numbered by ease; Gitpod upload method removed

Home page:
- VitePress hero with clear actions, larger hero image
- How-it-works pipeline diagram shared as a component (responsive via
  container queries), use-case grid, bigger video tiles without the
  image lightbox, refreshed press coverage list, functions pills
- Support section pointing to Theengs Bridge and
  github.com/sponsors/1technophile

Upload flow:
- Decision-oriented upload landing page (journey strip, method cards,
  comparison table)
- Pre-flight checklist and driver troubleshooting on the web installer
- Guided environment picker (bridge + hardware wizard) replacing the
  filter chips, with manifest-verified recommendations
- Post-flash next-steps card linking to the portal and verification

Board images:
- custom_img key in environments.ini and board photos for all
  web-flashable environments (licenses recorded); private prod_env.ini
  environments excluded from boards-info.json

Corrections:
- RF frequency coverage stated as 433/315/868/915MHz
- Removed references to the retired compatible.openmqttgateway.com
  site (BLE list is decoder.theengs.io), the discontinued Theengs
  Plug, and the private sponsor forum


Claude-Session: https://claude.ai/code/session_01TYysQW8tpmt1dWWuzKhTLi

Co-authored-by: Florian <1technophile@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docsgen/boards-info.js

@@ -214,11 +214,27 @@ function collectBoardsInformations(sections, { includeTests = false } = {}) {
     return rows;
 }
 
+// pio project config resolves extra_configs, which pulls in user-specific
+// files like prod_env.ini; only environments declared in environments.ini
+// belong in the published boards list.
+function publicEnvironmentNames() {
+    const fs = require('fs');
+    const path = require('path');
+    const ini = fs.readFileSync(path.resolve(__dirname, '..', 'environments.ini'), 'utf8');
+    const names = new Set();
+    for (const match of ini.matchAll(/^\[env:([^\]]+)\]/gm)) {
+        names.add(match[1].trim());
+    }
+    return names;
+}
+
 function loadBoardsInfo(options = {}) {
     const { includeTests = false } = options;
     const config = rowConfigFromPlatformIO();
     const sections = convertJsonToSections(config);
-    return collectBoardsInformations(sections, { includeTests });
+    const rows = collectBoardsInformations(sections, { includeTests });
+    const publicEnvs = publicEnvironmentNames();
+    return rows.filter(row => publicEnvs.has(row.Environment));
 }
 
 function ensureDir(dir) {