feat: narrow, but always open "planned actions"

[bjoern-michaelsen-freiheit]

• reduced width of "planned actions" aside
• always keep the aside open, and give it a primary color background to provide
  some hint on space separation
• reduce whitespace use in planned actions
• hide disabled apply button when there is nothing to apply. Note that the
  "lock message" input is also hidden, if there is no lock: if one adds a lock
  action to an empty plan, previously the input appeared, while the apply
  button was already there. The apply button stays disabled, but for different
  reasons (before: nothing to apply, after: missing lock message)

Ref: SRX-MVHTKH

[bjoern-michaelsen-freiheit]

old:

new: