[deckhouse-cli] Fix changelog.yaml doesnt exist

[Glitchy-Sheep]

Summary

d8 mirror pull without --deckhouse-tag "fails to generate deckhousereleases.yaml".
But it exists in the image itself (on release channel).

INFO   Generating DeckhouseRelease manifests
WARN   generate DeckhouseRelease manifests: Build manifest for version "v1.74.15":
       Extract changelog from release image: changelog.yaml: file does not exist

Additionally, every run produces 5 misleading warnings for install-standalone:

INFO  [1 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:beta
WARN  ⚠️ Not found in registry, skipping pull
INFO  [2 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:early-access
WARN  ⚠️ Not found in registry, skipping pull
INFO  [3 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:stable
WARN  ⚠️ Not found in registry, skipping pull
INFO  [4 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:rock-solid
WARN  ⚠️ Not found in registry, skipping pull
INFO  [5 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:alpha
WARN  ⚠️ Not found in registry, skipping pull

These look like errors but are harmless - install-standalone registry simply has no channel tags (only versioned like v1.74.15):

The warnings confuse users who cannot tell if something is actually broken.

Problems & Solutions

1. Wrong OCI layout in manifest generation

Problem: platform.go:698 reads release-channel images from svc.layout.Deckhouse (core images) instead of svc.layout.DeckhouseReleaseChannel (where changelog.yaml actually lives).

Solution: Pass svc.layout.DeckhouseReleaseChannel.

2. Premature gzip reader close in file extraction

Problem: extract_file.go calls decompressedLayer.Close() on filename mismatch, then continue tries to read the next tar entry from a closed reader. The whole layer is skipped after the first non-matching file.

Solution: Remove Close() from the mismatch branch.

3. Missing error handling after GetImage

Problem: deckhouse_releases.go printed GetImage() error via fmt.Printf and continued with nil image, causing panic.

Solution: Log via svc.userLogger.Warnf and continue to the next version (skip failed image, do not interrupt pull).

4. False warnings for install-standalone

Problem: FillForChannels() adds channel tags (alpha, beta, stable...) for install-standalone, but this registry only has versioned tags. Confirmed via crane ls.

Solution: Skip channel tags for install-standalone in FillForChannels().

Refactoring

• Removed dead GenerateDeckhouseReleaseManifestsForVersions function and its test-only helper
• Moved internal/mirror/manifests/deckhouse_releases.go into internal/mirror/platform/ (the only consumer), deleted the now-empty manifests package
• Renamed GenerateDeckhouseReleaseManifestsForVersionsNew to writeDeckhouseReleaseManifests (unexported, dropped New suffix)
• Made it a method on *Service to use svc.userLogger instead of fmt.Printf
• Added unit tests for generateDeckhouseRelease and extractReleaseInfoForDeckhouseRelease

Before / After

d8 mirror pull /tmp/test \
  --source registry.deckhouse.ru/deckhouse/ce \
  --license <TOKEN> \
  --since-version v1.74.0 \
  --no-modules --no-security-db

Before:

INFO  [1 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:beta
WARN  ⚠️ Not found in registry, skipping pull
INFO  [2 / 6] Pulling registry.deckhouse.ru/deckhouse/install-standalone:early-access
WARN  ⚠️ Not found in registry, skipping pull
...                                                          (x5 false warnings)
INFO   Generating DeckhouseRelease manifests
WARN   generate DeckhouseRelease manifests: Build manifest for version "v1.74.15":
       Extract changelog from release image: changelog.yaml: file does not exist

• deckhousereleases.yaml missing from output
• 5 confusing warnings for install-standalone on every run

After:

INFO  [1 / 1] Pulling registry.deckhouse.ru/deckhouse/install-standalone:v1.74.15
INFO   Generating DeckhouseRelease manifests
INFO   Searching for Deckhouse built-in modules digests

• deckhousereleases.yaml generated correctly
• No false warnings