fix: harden exception handling, break ARC cycles, sync license/client

Replace bare except: with CatchableError across storage, query, Raft,
backup, and protocol code so Defects are not swallowed. Break uncollectable
ARC cycles in server shard/gossip callbacks via Server-owned refs and
cursor locals. Align package license with LICENSE (BSD-3-Clause), sync
README version, and point test_all at the canonical clients/nim baradb
client (parseConnectionString + aliases).

src/barabadb/storage/compaction.nim

@@ -58,7 +58,7 @@ proc rebuildFromLSM*(cs: CompactionStrategy, db: LSMTree) =
   cs.clear()
   cs.dataDir = db.dir
   for sst in db.sstables:
-    let size = try: int(getFileSize(sst.path)) except: sst.entryCount * 64
+    let size = try: int(getFileSize(sst.path)) except CatchableError: sst.entryCount * 64
     cs.addTable(SSTableMeta(
       path: sst.path,
       level: sst.level,
@@ -143,7 +143,7 @@ proc compact*(cs: CompactionStrategy, level: int): CompactionResult =
   var sst = writeSSTable(final, outputPath, level + 1)
 
   # Use actual file size instead of rough guess
-  let actualSize = try: getFileSize(outputPath) except: final.len * 64
+  let actualSize = try: getFileSize(outputPath) except CatchableError: final.len * 64
 
   let outputMeta = SSTableMeta(
     path: outputPath,
@@ -159,7 +159,7 @@ proc compact*(cs: CompactionStrategy, level: int): CompactionResult =
   let (ok, msg) = verifySSTable(outputPath)
   if not ok:
     echo "[ERROR] Compaction output verification failed: ", msg
-    try: removeFile(outputPath) except: discard
+    try: removeFile(outputPath) except CatchableError: discard
     return CompactionResult()
 
   # Remove old SSTable files

src/barabadb/storage/gate.nim

@@ -18,13 +18,15 @@ var
 
 proc initStorageGate*() =
   ## Idempotent when called from a single thread at startup.
+  ## Must run before multi-threaded accept (HTTP workers / TCP).
   if not gInited:
     initLock(gGate)
     gInited = true
 
 proc acquireStorageGate*() {.inline.} =
   ## Prefer calling initStorageGate() once at process start (main).
-  ## Lazy-init is allowed for unit tests (single-threaded).
+  ## Lazy-init is only safe for single-threaded unit tests — concurrent
+  ## first-time init races on gInited / initLock.
   if not gInited:
     initStorageGate()
   acquire(gGate)

src/barabadb/storage/lsm.nim

@@ -473,7 +473,7 @@ proc listLegacySSTables*(dir: string): seq[(string, uint32)] =
         let sst = loadSSTable(path)
         if sst.fileVersion < SSTableVersion:
           result.add((path, sst.fileVersion))
-      except:
+      except CatchableError:
         discard
 
 proc migrateSSTable*(path: string): bool =
@@ -595,7 +595,7 @@ proc checkStorageConsistency*(db: LSMTree): seq[string] =
       let j = parseJson(readFile(manifestPath))
       for node in j{"sstables"}:
         manifestPaths.add(node{"path"}.getStr())
-    except:
+    except CatchableError:
       result.add("MANIFEST is corrupt or unreadable")
       return
 

src/barabadb/storage/wal.nim

@@ -77,7 +77,7 @@ proc parseWalSequence*(filename: string): int64 =
       result = parseBiggestInt(numStr)
     else:
       result = 0
-  except:
+  except CatchableError:
     result = 0
 
 proc listWalArchive*(dir: string): seq[WalSegment] =
@@ -90,7 +90,7 @@ proc listWalArchive*(dir: string): seq[WalSegment] =
     if kind == pcFile and path.endsWith(".log"):
       let seqNum = parseWalSequence(extractFilename(path))
       if seqNum > 0:
-        let size = try: getFileSize(path) except: 0
+        let size = try: getFileSize(path) except CatchableError: 0
         result.add(WalSegment(sequence: seqNum, path: path, size: size))
   result.sort(proc(a, b: WalSegment): int = cmp(a.sequence, b.sequence))
 
@@ -140,7 +140,7 @@ proc maybeRotate*(wal: var WriteAheadLog) =
   ## Rotate if current WAL exceeds max segment size.
   if wal.maxSegmentSize <= 0:
     return
-  let currentSize = try: getFileSize(wal.path) except: 0
+  let currentSize = try: getFileSize(wal.path) except CatchableError: 0
   if currentSize >= wal.maxSegmentSize:
     wal.rotate()