Related to #1175 #1004 #1153

The plan

• remove public facing "gh aw install" and "gh aw uninstall" (internalize the clone to /tmp only, remove docs, remove commands etc).
• adjust "gh aw add" to use actions syntax "gh aw add owner/repo/path/workflow@main" for remote references. the ".md" is optional and a whole directory of workflows can be installed
• adjust agentics to not use "@include" for now. internalize XPIA and link generation
• add "source" feature
• have "gh aw add" insert "source"
• implement "gh aw update"
• allow "@include " to also be "@import "
• adjust "gh aw add" to extrude the workflows being added and adjust "@include " to "@import "

Possibly also

• allow "import: " in frontmatter, identical to "@import " in markdown