docs: update BSTVC homepage links and companion tools - #3

Summary

• Update visible BSTVC GitHub links from songbi123 to bayesianstvc.
• Add the Chinese BSTVC desktop application website, a compact transparent desktop logo, and an English-version coming-soon note.
• Reduce the README header logo to 96 px and the WeChat QR code to 120 px.
• Remove the two CRAN Logs download badges.
• Move INLA Process Monitor to a later Additional companion tool section after the changelog.
• Keep README.Rmd and README.md synchronized.

Validation

• git diff --check passed.
• GitHub branch rendering was inspected at a 718 px viewport: the header logo rendered at 102×96 px, desktop logo at 124×104 px, and QR code at 120×120 px.
• The new desktop logo is a 512×512 RGBA PNG with transparent background.
• PR status is MERGEABLE / CLEAN.
• Badge and DOI URL checks were completed previously; the failed CRAN version badge and the two requested download badges are absent.
• R rendering was not run because Rscript is not available in the current environment.