chore(release): prepare 1.2.0

[hongjr03]

Summary

• Bump the server and VS Code extension versions to 1.2.0.
• Add bilingual 1.2.0 changelog pages with PR authors, contributors, and demo images.
• Update feature docs for code actions, macro hover/navigation/references, macro argument inlay hints, and struct document symbols.
• Include the VS Code package CI fix from fix(build): repair VS Code package CI #242 and remove Alpine arm64 package targets.

Closes #236.

Validation

• git diff --check
• npm --prefix docs run build
• cargo check -p vide
• cargo check -p xtask
• npm --prefix editors/vscode run typecheck
• npm --prefix editors/vscode run test

[github-actions]

Docs preview: https://vide.pascal-lab.net/preview/pr-243/