Split common into primitives and runtime layers

Reorganize src/common per issue #5963: move building blocks under
primitives/ and services/integration under runtime/. Preserve existing
common/* import paths via TypeScript path mapping. Add src/ARCHITECTURE.md
documenting modules and goals.

Fix two relative imports broken by the directory depth change.

Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>

bin/esbuild.mjs

@@ -190,7 +190,9 @@ if (config.addon) {
     ...outConfig,
     entryPoints: [
       'src/browser/**/*.ts',
-      'src/common/**/*.ts',
+      'src/common/primitives/**/*.ts',
+      'src/common/runtime/**/*.ts',
+      'src/common/*.ts',
       'src/headless/**/*.ts'
     ],
     outdir: 'out-esbuild/'

bin/publish.js

@@ -81,7 +81,7 @@ function checkAndPublishPackage(packageDir, repoCommit, peerDependencies, update
 
   // Update Version.ts with the new version
   if (updateVersionTs) {
-    const versionTsPath = path.join(packageDir, 'src/common/Version.ts');
+    const versionTsPath = path.join(packageDir, 'src/common/primitives/Version.ts');
     const versionTsContent = fs.readFileSync(versionTsPath, 'utf8');
     const updatedVersionTs = versionTsContent.replace(
       /export const XTERM_VERSION = '[^']+';/,