fix version startup and imported encodings

[matveynator]

What changed

• handle clean --version, -version, and -v invocations before storage-path and server flag initialization
• update NetChan to the lazy-logger change from start logger only when used netchan#4
• remove package-level fallback workers for registration confirmations, import cancellation, trial previews, and publish progress
• keep valid UTF-8 bytes as UTF-8 before heuristic scoring can reinterpret them
• normalize accidental MySQL UTF-8 charset/collation labels such as utf8mb4_unicode_ci
• normalize heuristic scores by document length and expose the selected encoding source/certainty in download results
• rewrite charset declarations only inside HTML <meta> tags, leaving JavaScript/JSON text untouched
• log uncertain import encoding decisions with their URL and source

Root cause

https://kmv.ru/for-home.html currently returns 170,977 valid UTF-8 bytes and declares UTF-8 in both HTTP and HTML metadata. The old whole-document scoring still selected KOI8-U because its length-dependent score outweighed the fixed UTF-8 preference, turning Для дома into п■п╩я▐.

Separately, NetChan started its logging goroutine from package init, so it ran before SiteBrush could process --version.

User impact

Version commands now print exactly one version line with no SiteBrush storage creation or NetChan startup log. Large UTF-8 pages retain their original text, legacy Cyrillic fallbacks remain supported, and charset-like strings embedded in scripts are no longer modified.

Checks

• GOCACHE=/private/tmp/sitebrush-gocache go test ./pkg/...
• GOCACHE=/private/tmp/sitebrush-gocache go test ./pkg/crawler -count=1
• targeted root tests for version command, legacy Windows-1251 import, and charset rewriting
• GOCACHE=/private/tmp/sitebrush-gocache go vet ./pkg/crawler
• live KMV check: encoding=utf-8 source=http certain=true expected_text=true mojibake=false bytes=170977
• built binary returned only version-live-check for all three version flags
• git diff --check

The full root suite has the same nine pre-existing failing tests on this branch and clean origin/main; no additional failing test was introduced.