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.
- StoreOutput now returns output hash for immediate retrieval
- Cache misses now serve from disk file after storing (same as hits)
- Log served_bytes from actual io.Copy result (avoids stat calls)
- Remove ContentLength field usage for cache hits (stream from file)
- Fix tests to properly check all return values
