ADR-0046 Accepted — First-class Media Workload entity

[znerol2]

ADR-0046 — First-class Media Workload entity — is Accepted and merged to main.

A Media Workload is now a first-class concept: an assembly of Media Functions for a production (EBU DMF Reference Architecture, Annex B Fig B1), modelled as a tag-derived grouping over NetBox instance records — no new graph object. This adds the assembly layer that ADR-0037 deliberately deferred; ADR-0037's function-instance inventory stays intact underneath.

The decision in brief (converged in RFC discussion #190, codex-cross-checked RFC 3 rounds + ADR 2 rounds → PASS):

• Membership via NetBox tag workload:<slug>, exactly 0-or-1 per service (zero → explicit unassigned).
• The six-stage EBU lifecycle is workload-level; v0.2 derives only Provision/Configure/Operate and joins health by service/instance identity, not the collapsing app rollup.
• Launchers must preserve non-owned tags (hard prerequisite) so workload:* survives the deploy lifecycle.
• Additive IA/API split — "Media Workloads" = the assembly; the flat surface becomes "Media Functions" (/api/media-function-instances).
• Narrow catalog fix — new ebu.media_function_type (exactly one of vertical | media_function_type per entry); mxl-hello is retired (superseded by the videotest workload), removing its layer:4/invalid-vertical anomaly.

First worked example: the videotest workload = mxl-videotestsrc + mxl-videotest-view + their flow.

Read: ADR-0046 · Discussion: #190 · Amends: ADR-0037

Implementation lands as codex-gated slices under #189 (launcher tag-preservation, catalog schema, console workload grouping, NetBox backfill) and #193 (mxl-hello retirement).