* refactor(browser): split installation and profile abstractions
A Chromium installation shares one master key across its profiles, but
modeling each profile as its own Browser re-derived the key per profile.
Browser now represents one installation holding its profiles and derives
the key once; new types.Profile/ExtractResult/CountResult carry per-profile
results.
* style: gofumpt safari_test.go
* test(chromium): rename shadowed loop var to path
Roger