[deckhouse-cli] Backport --since-version fix to 0.33

[Glitchy-Sheep]

Note

Backport of the --since-version fix from #510 to release-1.33 (CLI 0.33).

Summary

Users of CLI 0.33 can now include older platform releases in a mirror bundle with --since-version.

Problem

• The command parses the flag but never passes its value to platform discovery.
• The platform code also uses the later version as the lower bound, contrary to the documented behavior.

Fix

• Pass the requested version from the command through the pull service to platform discovery.
• Use the earlier of Rock Solid and the requested version as the inclusive lower bound.
• Keep the latest patch per minor and the release-channel versions within the selected range.
• Update the documentation to explain how the flag extends the default range.

Before / After

With Rock Solid at 1.68.0:

Flag	Before	After
--since-version 1.67.0	Lower bound stays at 1.68.0	Lower bound moves to 1.67.0
--since-version 1.70.0	Lower bound stays at 1.68.0	Lower bound stays at 1.68.0

Tests

• TestPullCommandSinceVersion covers the real command, version boundaries, and conflicting flags.
• Platform tests cover latest patches, release-channel versions, and LTS-only registries.
• CI checks pass: Test, Lint, Build for PR, and DCO.