[REF] use single main branch with per-version config directories

Replace per-branch versioning (16.0, 18.0...) with a single main branch
containing version-specific subdirectories under config/.

Structure:
- config/common/: shared files deployed to all versions
- config/16.0/: Odoo 16.0 specific configs (pylintrc, ruff, pre-commit)

The deploy workflow now:
- Triggers on push to main
- Auto-detects available versions from config/*/
- For each target repo, deploys common + version-specific files

Also enables Gitea native cache in pre-commit workflow.

config/common/.prettierrc.yml

@@ -0,0 +1,8 @@
+# Defaults for all prettier-supported languages.
+# Prettier will complete this with settings from .editorconfig file.
+bracketSpacing: false
+printWidth: 88
+proseWrap: always
+semi: true
+trailingComma: "es5"
+xmlWhitespaceSensitivity: "strict"