Cited memory over DSHs lossless session log

Key features

• Cited memory over DSH's lossless session log.
• /.dsh/memory/ /.md — project + feedback memories, keyed by the session cwd's basename.
• memory_read(name) — the full memory file: name, type, description, body, citations.
• Distilled facts that can always escalate back to the exact original context.
• /.dsh/memory/_user/.md — user-type (cross-project) memories.