hate_crack/config.json.example and the root copy had drifted (10 keys
missing from the packaged copy, 4 dead PassGPT keys still shipped,
hcatPath disagreeing). Replace the packaged copy with a symlink to the
root file so there is exactly one set of shipped defaults, and add a
test guard asserting the two stay identical.
Also stop writing missing keys back into the user's config.json on
load: merge defaults into the in-memory config_parser dict only. A
stale example file previously meant wrong defaults got persisted to
disk permanently; now the effective values are always whatever config.json.example
currently ships, and users are never surprised by keys silently
appearing in their config file.
Fixes#150
