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 rebased onto the current visible main base exposed by the connector (1dfa4b6067904fc1ebd5c708b3dcd8c379659159).

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 formalize/“freeze” the boundary between the umbrella SourceOS metadata-plane contracts and a separate operational evidence-fabric contract family (including ownership and naming/discriminator rules).

Changes:

• Introduces an ADR describing evidence-fabric boundaries, reserved names, and the kind vs type discriminator rule.
• Documents repo ownership split across SourceOS-Linux, SocioProphet, and SociOS-Linux.

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[Copilot]

ADR filenames and titles in this repo follow the numbered pattern (e.g., docs/adr/0005-... with a # ADR-0005: ... heading). Consider renaming this to the next available number (currently 0006-...) and updating the H1 to match, so it stays consistent with the existing ADR index/sorting.

Suggested change

	# ADR: Evidence Fabric Boundaries and Contract Ownership (v0.1)
	# ADR-0006: Evidence Fabric Boundaries and Contract Ownership (v0.1)

[Copilot]

The ADR header metadata format here diverges from the project ADR template: other ADRs use a top metadata block like **Status:** ..., **Date:** ... (and sometimes **Deciders:** ...) followed by a --- divider. Updating this ADR to match the template will keep the collection uniform and easier to scan.

Suggested change

	## Status
	Proposed.
	**Status:** Proposed
	---