refactor(platform): phase 6/9 migrate daemon IPC and lifecycle mechanics

[zackees]

Parent: #1306
Depends on: phase 5 filesystem migration

Scope

Move fbuild-owned host IPC/lifecycle primitives behind fbuild_core::platform::ipc and the existing process/fs facades:

• native endpoint/listener/connect/peer behavior not already abstracted by running-process or interprocess;
• daemon startup, endpoint readiness, lock ownership, and native lifecycle seams;
• owner-only permissions and peer/process facts used by fbuild.

Do not reimplement running-process broker/session behavior or change HTTP/protobuf compatibility. Delete exact migrated ledger rows.

Acceptance criteria

• RED characterization covers daemon acquisition, endpoint readiness, owner death, and native IPC seams.
• Shared broker/daemon code names no concrete socket/pipe or native peer type.
• Existing running-process adoption, direct-mode fallback, daemon isolation, and HTTP behavior remain compatible.
• Before/after ledger totals and RED -> GREEN evidence are recorded.
• Focused daemon tests, three-host CI, workspace check/clippy, and repo tests are GREEN.