Link the video guides from README, README.sv, and the in-app Guide page

Commit all 7 recorded clips to docs/videos/ (alongside the existing docs/screenshots/)
instead of leaving them in the gitignored video-guides/ folder from the earlier
feasibility spike - they're meant to be shipped, discoverable assets now, not scratch
output. scripts/record-video-guides.mjs writes there by default going forward.

Added a "Video Guides" section to README.md/README.sv.md (Getting started + Interface
tour groups) and a matching in-app "Video guides" panel on the Guide page, right after
the overview cards - the most discoverable spot for a brand-new user. Links point at
/docs/videos/<name>.mkv, served by the server's existing /docs static route.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "rc-racecore",
-  "version": "1.19.0",
+  "version": "1.20.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "rc-racecore",
-      "version": "1.19.0",
+      "version": "1.20.0",
       "hasInstallScript": true,
       "dependencies": {
         "better-sqlite3": "^12.11.1",