mnemo 1.4.0 — soft-delete residual probes (+ 1.3.0 clean memory)

1.4.0 — soft-delete residual probes for the ErasureAuditor (from an r/RAG thread: 'the API returned 200' and 'it's gone' are two different things — a store can report a delete as done while the data physically survives until a background compaction/vacuum/GC that may never trigger). Zero new deps — each probe calls only the client you pass.

• QdrantSoftDeleteProbe — deleted points under the optimizer deleted_threshold (0.2 / 1000-min).
• PgVectorSoftDeleteProbe — MVCC n_dead_tup (dead-until-VACUUM).
• S3VersioningProbe — a 'delete' is just a delete marker over a live version.
• SoftDeleteProbe — generic hook for the long tail (Chroma compaction, observability spans, CDC/Kafka, embedding-provider logs).

Also includes 1.3.0 — clean memory (not separately released): admit() write-admission gate (kills exact/near-exact re-extraction bloat), why_recalled() + memory_report() inspector. All opt-in; 45 tests pass.