ByteFrame previously panicked on out-of-bounds reads, which crashed
the server when parsing malformed client packets. Now sets a sticky
error (checked via Err()) and returns zero values, matching the
encoding/binary scanner pattern. The session recv loop checks Err()
after parsing to reject malformed packets gracefully.
Also replaces remaining panic("Not implemented") stubs in network
packet Build/Parse methods with proper error returns.
Fix unchecked error returns on bf.Seek(), db.Exec(), QueryRow().Scan(),
pkt.Build(), logger.Sync(), and binary.Write() calls. The linter now
passes with 0 errors, build compiles, and all tests pass with -race.
Re-enable the golangci-lint job in CI (disabled Oct 2025), update to
Go 1.25 and golangci-lint-action v7. Fix errcheck, gosimple S1009,
staticcheck SA4031 and SA2001 errors across 54 files. Remaining ~39
lint errors will be addressed in follow-up commits.
