Seed device fleet and document agent

Populate varied device posture states in seed data and link the
probo-agent release guide from AGENTS.md.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

AGENTS.md

@@ -12,6 +12,7 @@ Detailed guides for specific subsystems live in `contrib/claude/`:
 - [`contrib/claude/httpclient.md`](contrib/claude/httpclient.md) — HTTP client (kit/httpclient, SSRF protection by default, connector wiring)
 - [`contrib/claude/gid.md`](contrib/claude/gid.md) — Global identifiers (GID layout, TenantID, entity type registry)
 - [`contrib/claude/coredata.md`](contrib/claude/coredata.md) — Data access layer (Scoper, SQL patterns, filters, order fields, migrations)
+- [`contrib/claude/ownership.md`](contrib/claude/ownership.md) — Resource ownership (membership profile vs identity; provisional)
 - [`contrib/claude/logging.md`](contrib/claude/logging.md) — Structured logging (PII-free rules, field helpers, logger wiring)
 - [`contrib/claude/graphql.md`](contrib/claude/graphql.md) — Go GraphQL backend (gqlgen, @goModel, connection types, cursor pagination)
 - [`contrib/claude/mcp.md`](contrib/claude/mcp.md) — MCP API patterns (specification.yaml, mcpgen, resolvers, type helpers)