Refactor Stats to typed keys and fix peak-tracking race

Replace the map-backed Stats counter with a fixed [numStats]int array
indexed by a new StatKey enum, eliminating the hand-maintained map
initialization and the parallel string-keyed Values() map.

Fix a check-then-act race in the connection peak tracking: the old
Get-then-Set across two lock acquisitions could let concurrent
connections clobber each other's update. The new atomic Max method does
the compare-and-set under a single lock.

Values() now returns a typed StatValues struct whose JSON tags preserve
the existing /api/v1/stats wire format.

0 files changed, 0 insertions, 0 deletions