feat: port session 17 — Store Interfaces & Memory Store

- StoreTypes: IStreamStore/IConsumerStore interfaces, StreamConfig/ConsumerConfig,
  all enums (StorageType, RetentionPolicy, DiscardPolicy, AckPolicy, etc.),
  StreamState, SimpleState, LostStreamData, DeleteBlocks/Range/Slice, StoreMsg
- MemStore: JetStreamMemStore with full message CRUD, state tracking, age expiry
- ConsumerMemStore: ConsumerMemStore with delivery/ack state tracking
- DiskAvailability: cross-platform disk space checker
- 135 features complete (IDs 3164-3194, 2068-2165, 827-832)

reports/current.md

@@ -1,6 +1,6 @@
 # NATS .NET Porting Status Report
 
-Generated: 2026-02-26 20:50:51 UTC
+Generated: 2026-02-26 21:02:04 UTC
 
 ## Modules (12 total)
 
@@ -13,9 +13,9 @@ Generated: 2026-02-26 20:50:51 UTC
 
 | Status | Count |
 |--------|-------|
-| complete | 1601 |
-| n_a | 82 |
-| not_started | 1897 |
+| complete | 1736 |
+| n_a | 77 |
+| not_started | 1767 |
 | stub | 93 |
 
 ## Unit Tests (3257 total)
@@ -36,4 +36,4 @@ Generated: 2026-02-26 20:50:51 UTC
 
 ## Overall Progress
 
-**2194/6942 items complete (31.6%)**
+**2324/6942 items complete (33.5%)**

reports/report_77403e3.md

@@ -0,0 +1,39 @@
+# NATS .NET Porting Status Report
+
+Generated: 2026-02-26 21:02:04 UTC
+
+## Modules (12 total)
+
+| Status | Count |
+|--------|-------|
+| complete | 11 |
+| not_started | 1 |
+
+## Features (3673 total)
+
+| Status | Count |
+|--------|-------|
+| complete | 1736 |
+| n_a | 77 |
+| not_started | 1767 |
+| stub | 93 |
+
+## Unit Tests (3257 total)
+
+| Status | Count |
+|--------|-------|
+| complete | 319 |
+| n_a | 181 |
+| not_started | 2533 |
+| stub | 224 |
+
+## Library Mappings (36 total)
+
+| Status | Count |
+|--------|-------|
+| mapped | 36 |
+
+
+## Overall Progress
+
+**2324/6942 items complete (33.5%)**