New Features: postal code, private IP override, file logging, hot-reload of mmd Database, Version Upgrades: Go (1.25) , Traefik, semantic, Fixes: Private IP Lookups, missing DB... - #13

X-GeoIP2-PostalCode header — postal/ZIP code is now populated from GeoLite2-City.mmdb and forwarded as a request header; always XX when using the Country database
X-GeoIP2-PrivateIP header — set to true when the client IP is private, loopback, or link-local and no database lookup was performed
Private IP override — new config fields privateIPCountry, privateIPRegion, privateIPCity, and privateIPPostalCode allow operator-defined location values to be returned for private/LAN IPs instead of triggering a (failing) database lookup
Per-request file logging — new logFilePath config field writes one structured line per request to a separate log file; format: <RFC3339> ip=<ip> country=<cc> region=<rc> city=<city> postal=<zip> private=<bool>
Database hot-reload — new dbRefreshInterval config field (in seconds) enables periodic checks for .mmdb file changes on disk; the new reader is swapped in atomically under a sync.RWMutex without restarting Traefik
Reverse-proxy awareness — new preferXForwardedForHeader config field uses the first IP from X-Forwarded-For instead of RemoteAddr (e.g. when running behind Cloudflare)
Panic-safe DB loading — panics from the mmdb parser (corrupt or truncated files) are caught via recover() and returned as regular errors; the middleware continues to serve requests with Unknown values
Bug Fixes
Private IPs previously caused spurious lookup errors in the Traefik log; they are now short-circuited before the database is consulted
X-GeoIP2-IPAddress was incorrectly set to XX when the database was unavailable; it now always reflects the resolved client IP regardless of lookup outcome
isPrivateIP now covers loopback (127.x, ::1) and link-local (169.254.x, fe80::) in addition to RFC 1918 ranges
Global lookup variable replaced by a per-instance field protected by sync.RWMutex — multiple middleware instances no longer share state

Internal / Chore

README.md — corrected header name X-GeoIP2-IsPrivate → X-GeoIP2-PrivateIP (3 occurrences); was inconsistent with the actual header constant in code
Dockerfile — base image updated from traefik:2.4.9 to traefik:v3.3; outdated GiGInnovationLabs references in comments updated to traefik-plugins
.traefik.yml — testData extended with all new config fields: privateIPCountry, privateIPRegion, privateIPCity, privateIPPostalCode, dbRefreshInterval, logFilePath
package.json — semantic-release bumped from ^20.1.0 to ^24.0.0; @commitlint/config-conventional bumped from ^17.4.0 to ^19.0.0; @semantic-release/github ^11.0.0 added as explicit dependency (was referenced in .releaserc.yaml but missing from package.json)
package-lock.json — removed; will be regenerated by CI on next run
.golangci.yaml — removed duplicate scopelint and ifshort entries; added mnd alongside deprecated gomnd (renamed in golangci-lint v1.56); removed deprecated empty skip-files and skip-dirs directives
Go version updated to 1.25