Semantic owner registration must be its own project-owned task, not a step inside the code-index mount

[ScriptedAlchemy]

Context

install_semantic_activation_runtime_owner is called inside the code-index mount closure in crates/tracedecay/src/daemon/project_composition/code_index_activation.rs. A demand-driven activation can run before register_project_open_production_owners registers the configuration runtime, so the install fails with the typed "semantic activation reconciler requires a registered configuration runtime" error. Until 9c1fd5c5e that error was propagated with ? and aborted the whole text/graph mount: semantic readiness was gating code-index warming, the inversion of the lifecycle order (project open → feedback/session → LSP → code-index warming → semantic readiness). 9c1fd5c5e is a containment fix: it logs project_open_phase phase=semantic_activation_owner outcome=degraded and keeps the mount; the advisory-runtime owner re-registers the semantic owner idempotently on the first serving generation.

Durable shape (architecture review, 2026-09-06)

• One project-owned semantic registration task, outside the code-index mount closure, triggered when both the configuration registration and the production semantic runtime exist. Source readiness then governs activation/restore work, not whether unrelated text/graph mounting succeeds.
• Do not put it behind successful advisory mounting or first graph seating as its sole trigger. Reuse the deferred-ownership infrastructure (project_open_owners/advisory_runtime/deferred.rs), but keep semantic registration independently scheduled and cancellable.
• Record a queryable semantic unavailable/degraded state (status/doctor), not just a warning line.
• Preserve identity/policy refusals; clean up partial registration on failure.
• The installer already requires the production semantic runtime, so moving it earlier without a later wake would lose registration.

Acceptance

• Code-index mount success never depends on semantic owner registration.
• A configuration-runtime registration race leaves a typed degraded semantic state that status reports and that heals without restart.
• fresh_committed_project_open_mounts_feedback_before_lsp and the semantic activation journey stay green.

Targets codex/tracedecay-total-redesign-plan-reopened (#707). Refs #901, #753.