The settings.json bootstrap only fires when the file is ABSENT, so a
settings.json on a preserved named volume never picks up config added in a
later image (e.g. the observational-memory / pi-fork blocks, a newly-enabled
model). Users had to hand-merge after every upgrade.
On start, when settings.json already exists, deep-merge the template into it
with 'jq -s ".[0] * .[1]"' (template first, live second) so the user's values
always win and only MISSING keys are filled from the template. Arrays are
leaves (a model the user removed is not re-added). Rewrites only when the
merge changes something, backs up the original first, and skips safely (no
clobber) if either file is invalid JSON. Opt out with PI_SETTINGS_MERGE=0.
Add a recreate-sanity-check assertion that settings.json carries the
observational-memory + pi-fork blocks after recreate.
Joakim Persson
41c2c2b716