Rethink dev - staging - production modes

[kapouer]

A site can be:

• compiled (transpiled and bundled and minified)
• hooked to git
• frozen (webmaster cannot change blocks, maybe only inline blocks or href)
• optimized (makes sense when frozen)
• assigned to a domain (and exposing sitemap to robots) or not

The workflow for a site is:

• debug: uncompiled, unfrozen, unoptimized, unassigned. Source is a git repo.
• dev: compiled, unfrozen, unoptimized, unassigned
• staging: compiled, frozen, optimized, unassigned
• production: compiled, frozen, optimized, assign

dev -> staging or dev -> production should be done by first making a copy of the current site in dev mode.
This should be a "smart" copy that doesn't copy "uploads" folder of the dev site, since uplods are immutable
they can be shared between all modes.

Then staging -> production is done using the same "site".
This way one can continue to develop the site while having a production site running.

Optimizing regroups:

• purge all unused elements (and their deps...)
• purge css by crawling "all" pages
• recompile all

Production versions are not necessarily erased - this way one can assign the domain to a previous production version.

git hooks should only apply to debug/dev mode.
In particular, git tags no longer do something specific (like update only production).
Only debug/dev mode shall allow reinstalling a site from git repository.

• mysite.pageboard.io always points to development site.
• mysite-commitish.pageboard.io points to a specific commit or tag of a staging copy.
• mydomain.com points to mysite-commitish.pageboard.io (internally) which is a staging copy that became production.

[kapouer]

As a consequence of this, the granularity of the client modules can be improved:

• all generic elements can be defined in a single module
• others are for external modules (private|unsupported|unmaintained)
  This won't change the way page bundles are built - just simplify maintenance and versioning.

This makes it clearer that a new element is needed: the "domain" - which is not exactly a "site".

Also "copy of site" is not that simple: the blocks generated by "users" (i.e. not webmaster) in production site must not be erased/modified when copying (from dev to production) the blocks generated by webmaster.