feat(discord/build): group image tags into main/minimal sections

[barnabasbusa]

Summary

• Deterministically sort manifest variants (beacon → validator → beacon-minimal → validator-minimal), so the "primary" image in the completion DM no longer depends on Go's random map iteration order. Previously Prysm could surface *-minimal as the lead image.
• Inline every tag into the embed as its own fenced code block, grouped into Images and Minimal images fields. Each tag gets a per-block copy icon on hover — the separate Copy tags button and its ephemeral reply are gone.
• Drop the completed cache, completedBuild type, HandleComponent/lookupCompleted/sweepCompleted/parseComponentID/respondEphemeral and completedRetention const — all only existed to back the button.
• Single-manifest clients (Geth, Reth, Lighthouse, Besu, Teku, Erigon, Lodestar…) render as one code block under Images, no minimal section.

Example output

Reth (single manifest):

Images

ethpandaops/reth:v1.5.0

Prysm / Nimbus-eth2 (4 manifests):

Images

ethpandaops/prysm-beacon-chain:v1.7.0-alpha.5

ethpandaops/prysm-validator:v1.7.0-alpha.5

Minimal images

ethpandaops/prysm-beacon-chain:v1.7.0-alpha.5-minimal

ethpandaops/prysm-validator:v1.7.0-alpha.5-minimal

Heads up

In-flight DMs (<2h old) that still carry the old Copy tags button will show "This interaction failed" on click, since the handler is gone. New DMs render in the new format.

Test plan

• Dispatch /build for a single-manifest client (e.g. Reth) and confirm one code block under Images, no minimal section.
• Dispatch /build for Prysm and confirm field order: Images (beacon, validator) then Minimal images (beacon-minimal, validator-minimal).
• Dispatch /build for Nimbus-eth2 and confirm both nimbus-eth2 and nimbus-validator-client tags appear correctly grouped.
• Hover a code block in the DM on desktop and verify the per-block 📋 copy icon copies just that tag.