docs: add ADR for evidence fabric boundaries and contract ownership

[mdheller]

Summary

Adds an ADR that freezes the boundary between the umbrella SourceOS metadata plane and the planned operational evidence fabric.

What this PR adds

• docs/adr/ADR-evidence-fabric-boundaries-v0-1.md

Why

The current ecosystem now has enough moving pieces that repo and contract ownership needs to be explicit before evidence-plane repos are created and implemented.

This ADR locks the following points:

• sourceos-spec remains the umbrella metadata-plane and governance contract layer
• the evidence fabric becomes a distinct operational contract family owned in SocioProphet
• runtime evidence objects should not reuse umbrella names like RunRecord
• operational evidence contracts use kind rather than type
• desktop-facing account and capture surfaces remain with SociOS-Linux

Current upstream posture

This PR was branched from the latest visible merged mainline commit currently available through the connector (07ac5c1aee1841276d21b887d2bdf8c6e6748a79).

Follow-on work

1. create the dedicated evidence-plane repo family in SocioProphet
2. align evidence-plane provenance/connector mappings upward to sourceos-spec
3. avoid absorbing operational custody schemas directly into sourceos-spec

[Copilot]

Pull request overview

Adds a new Architecture Decision Record (ADR) to define and “freeze” the boundary between the sourceos-spec umbrella metadata plane and a planned operational evidence fabric, clarifying contract naming and repo ownership.

Changes:

• Added an ADR describing evidence-fabric vs metadata-plane boundaries and reserved names.
• Documented repo ownership split across SourceOS-Linux, SocioProphet, and SociOS-Linux.
• Specified a discriminator convention for evidence-plane runtime contracts (kind vs type).

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[Copilot]

This ADR’s header/metadata format diverges from the existing ADR conventions in docs/adr (e.g., 0001–0005 use # ADR-000x: ... plus **Status:**, **Date:**, **Deciders:**, followed by a --- divider). Please align this ADR to the same structure (and consider numbering/renaming to the next ADR-0006 slot) so ADR tooling and directory ordering stay consistent.

Suggested change

	# ADR: Evidence Fabric Boundaries and Contract Ownership (v0.1)
	## Status
	Proposed.
	# ADR-0006: Evidence Fabric Boundaries and Contract Ownership (v0.1)
	**Status:** Proposed
	**Date:** TBD
	**Deciders:** TBD
	---

[mdheller]

@copilot Please fix failed checks

[mdheller]

Superseded by #13 after main moved again during landing. Keeping #12 only as the original first draft branch against the earlier visible base.

[Copilot]

@copilot Please fix failed checks

Done in 53644df. Merged main into the branch (which picks up the --spec=draft2020 fix for ajv-cli that was causing the JSON schema validation failures), and renamed/reformatted the ADR to 0006-evidence-fabric-boundaries.md following the existing convention (# ADR-0006: ... header, **Status:**/**Date:**/**Deciders:** metadata, --- divider).