Move HTTPFetcher, Config (was FetcherConfig), SSRF-safe dialer, rate
limiting, content-type validation, and related error vars from
internal/imgcache/fetcher.go into new internal/httpfetcher/ package.
The Fetcher interface and FetchResult type also move to httpfetcher
to avoid circular imports (imgcache imports httpfetcher, not the other
way around).
Renames to avoid stuttering:
NewHTTPFetcher -> httpfetcher.New
FetcherConfig -> httpfetcher.Config
NewMockFetcher -> httpfetcher.NewMock
The ServiceConfig.FetcherConfig field is retained (it describes what
kind of config it holds, not a stutter).
Pure refactor - no behavior changes. Unit tests for the httpfetcher
package are included.
refs #39
Define ContentHash, VariantKey, and PathHash types to replace
raw strings, providing compile-time type safety for storage
operations. Update storage layer to use typed parameters,
refactor cache to use variant storage keyed by VariantKey,
and implement source content reuse on cache misses.
Since signing_key is now required at config load time, sessMgr, encGen,
and signer are always initialized. Remove unnecessary nil checks that
were runtime failure paths that can no longer be reached.
- handlers.go: Remove conditional init, always create sessMgr/encGen
- auth.go: Remove nil checks for sessMgr
- imageenc.go: Remove nil check for encGen
- service.go: Require signing_key in NewService, remove signer nil checks
- Update tests to provide signing_key
