chore: initial monorepo scaffold

Setup pnpm workspaces with apps/{web,api} placeholders and shared
packages: tsconfig, eslint-config, shared, ui, db. Includes Prettier,
ESLint, Husky pre-commit, lint-staged, EditorConfig, VSCode settings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 2
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false