Add source-control intent registration and evidence bridge for gitea-sovereign

[mdheller]

Context

SocioProphet/gitea-sovereign PR #1 has merged the non-mutating PR-A scaffold for svc.substrate.source-control.

Merged baseline: SocioProphet/gitea-sovereign@5d85ab6a24502f60f15ef829235b6288a289d47e.

Requested change

Add an AgentPlane bridge for source-control intent registration and post-execution evidence emitted by gitea-sovereign.

Bridge surface needed

• source-control intent registration reference;
• source-control operation evidence artifact;
• blocked operation evidence artifact;
• divergence evidence artifact;
• receipt references compatible with AgentPlane run/replay/evidence style;
• no assumption that PR-A scaffold implies runtime readiness.

Authority boundary

AgentPlane remains canonical execution admission and evidence-producing run authority. gitea-sovereign registers source-control intent/evidence surfaces and consumes AgentPlane semantics.

Acceptance criteria

• Source-control intent/evidence bridge contract exists.
• Examples include allowed operation, blocked operation, and divergence cases.
• Bridge preserves AgentPlane evidence/replay posture.
• Bridge does not permit gitea-sovereign to bypass AgentPlane admission semantics.