Finish the lint remediation: script/cibuild exits 0 (closes #61)

Clears the final 80 golangci-lint findings under the canonical
.golangci.yml (sha256 021cc83f4e6fc7c31b95b34b846723dfcf20b66b7baeea1dc40406e643346bcb),
taking the repo from red to green: script/cibuild exits 0.

- wsl_v5 (60): blank line above defer/go statements sharing no variable
  with the line above; blank-line-only diff.
- sqlclosecheck (10): the package-local CloseRows helper hid the close
  from the analyzer. Helper removed; all 18 call sites now defer an
  inline rows.Close(), preserving the fatal-on-close-error path. No
  resource leak existed - the rows were always being closed.
- prealloc (3): append targets given a starting capacity.
- revive (3): package-name findings suppressed with per-site directives
  pending the naming decision tracked in #76.

No gosec suppressions are needed under the pinned linter. .golangci.yml,
Dockerfile, Makefile, .gitea/ and script/ are byte-identical to main.

Verified with script/cibuild (digest-pinned golangci-lint v2.12.2), not
make check - the latter resolves the linter from PATH and is not a
trustworthy gate here; see #78.

Closes #59.

internal/snapshot/scanner.go

@@ -624,11 +624,12 @@ func (s *Scanner) collectBatchFlushData(
 
 	collectStart := time.Now()
 
-	var (
-		allFileChunks []database.FileChunk
-		allChunkFiles []database.ChunkFile
-	)
-
+	// A pending file contributes one mapping of each kind per chunk, and
+	// an empty file contributes none, so the file count is only a rough
+	// starting capacity for the mapping slices; append grows them as
+	// needed. It is exact for the file and file-ID slices.
+	allFileChunks := make([]database.FileChunk, 0, len(canFlush))
+	allChunkFiles := make([]database.ChunkFile, 0, len(canFlush))
 	allFileIDs := make([]types.FileID, 0, len(canFlush))
 	allFiles := make([]*database.File, 0, len(canFlush))
 
@@ -1673,6 +1674,7 @@ func (s *Scanner) processFileStreaming(
 	if err != nil {
 		return fmt.Errorf("opening file: %w", wrapPermissionError(fileToProcess.Path, err))
 	}
+
 	defer func() { _ = file.Close() }()
 
 	var chunks []streamingChunkInfo