Insert-if-missing zsh baseline ordering across all 6 delivery mechanisms

[darkn3rd]

Summary

The .zshrc baseline (prompt/history/completion setup) used to be written by a single full-content files: step. Several other lessons (sdkman/rbenv/pyenv/asdf/go/rust/rvm/cpan) independently append their own lines into the same .zshrc/.bashrc. Since a file: step is a full overwrite, whichever kind of step (file vs append) a given tool happened to apply last to the same destination would silently win/wipe the other - Salt was the one tool that visibly hit this, papered over with a blanket order: last on every append.

This PR replaces the full-content write with three appends: entries (grouped by concern: prompt setup, shell options, completion system), reusing the existing appends:/append: mechanism rather than introducing a new step type. They're attached via a noop: zsh_baseline carrier placed in COMMON_AREA, which every tool already applies before any gated area - no needs:/meets: coupling required for 4 of 5 tools. Salt is the exception (its include:-based area pull-in doesn't reliably preserve common-before-areas by textual position), so it gets a small generic order: passthrough field instead of the old blanket order: last hack.

No bash/Ruby glue code was introduced to work around any tool's own gaps - where a tool was missing real support for the noop type (previously only exercised by the plain-bash-installer's windows.yml), a first-class case was added to that tool's own install_step dispatcher instead.

Changes

• scriptbox/config/ubuntu2204.yml: split files.ubuntu_default_zshrc into 3 concern-grouped appends: entries, attached via a new noop: zsh_baseline COMMON_AREA carrier (order: 1).
• resolve_order.rb / generate_chef_databag.rb: generic optional order: field, passed through to every generator (only Salt's template consumes it).
• Puppet/Chef/Ansible/Salt: added a real noop case to each install_step dispatcher (CFEngine needed none - it already no-ops silently for any unrecognized type).
• Salt's install_step.jinja: order: last on every append is now order: {{ step.get('order', 'last') }} - the baseline runs first via order: 1, every other append is unchanged.
• scriptbox/config/helpers/common.yml: fixed append_line() (bash + PowerShell) to create the destination file if missing, rather than silently no-op'ing - a real bug this change exposed, since every prior append target was guaranteed to already exist by some other step.

Test plan

• rake generate:all - all 5 CM-tool generators regenerate cleanly
• rake test - 76/76 passing
• Live-verified all 6 delivery mechanisms (Puppet, Chef, Ansible, Salt, CFEngine, plain bash installer), each both on a fresh box and re-provisioned/drifted: baseline lands first in .zshrc, in the correct internal order, before every other lesson's own appended lines, with no duplication on re-provision.