fix: image surfaces and dry-run reclaim semantics

[sjmiller609]

Summary

• include digest-only images in image listings and support deleting images by digest
• correct dry-run reclaim accounting so planned actions do not report applied reclaim bytes
• add reproducer coverage for the PR publish ts package #43 regressions in API, image manager, and guest-memory tests

Testing

• go test ./lib/images -run "Test(ListImages_IncludesDigestOnlyImages|DeleteImageByDigest)" -count=1
• go test ./lib/guestmemory -run TestTriggerReclaimDryRunDoesNotReportAppliedReclaim -count=1
• go test ./cmd/api/api -run "Test(ListImages_FilterByTagsIncludesDigestOnlyImages|DeleteImage_DigestOnlyImageDoesNotInternalError)" -count=1
• On deft-kernel-dev after bootstrap: go test ./lib/images ./lib/guestmemory ./cmd/api/api -count=1

Notes

• I did not add a fix for the intermittent snapshot fork 500 because we still do not have a deterministic local reproduction.

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Note

Medium Risk
Medium risk because it changes image storage enumeration and deletion semantics (including digest-based deletes) and adjusts reclaim accounting, which could affect user-visible API behavior and disk cleanup edge cases.

Overview
Images: Listing/metrics now enumerate images by digest metadata.json (not just tag symlinks), so digest-only images appear in ListImages and tag filtering. Deletion now supports digest references by removing any tags pointing at the digest and deleting the digest directory under a repository, with locking moved to cover tag resolution/removal and orphan checks.

Guest memory reclaim: dryRun no longer reports AppliedReclaimBytes (response or per-action) and avoids implying reclaimed memory unless a target was actually applied.

Tests/docs: Adds API and manager regression tests plus helpers for seeding digest-only metadata, adds a dry-run reclaim test, and appends branch verification notes in skills/test-agent/agents/test-agent/NOTES.md.

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[sjmiller609]

taking liberty to merge small fixes