lib: banner purge + WHY-only comment sweep (rule 8)

Every // ---- section banner dies (132 -> 0): names carry the WHAT.
Narration deleted (filename restatements, run-with lines, what-the-
next-line-does); every ref/hare cite, task cite, divergence, ABI/
layout contract, and ownership qualifier kept (borrowed-view lines
restored where the sweep over-cut). Comment-only proven: all 442
walk-workdir .s and 32 import-probe .s byte-identical before/after;
libbyteid 56-roster all-ID.

lib/bufio/stream.ww

@@ -2,24 +2,6 @@
 // Hare's bufio:: surface (ref/hare/bufio/{scanner,stream}.ha). Project
 // #94 fold-eFinal.
 //
-// Surface:
-//
-//   bufio.newscanner   (src: io.stream, maxread: i32) scanner
-//   bufio.newscannerbuf(src: io.stream, buf: []u8) scanner
-//   bufio.finish     (s: *scanner) void
-//   bufio.scanbyte   (s: *scanner) (u8  | io.eof | io.error | overflow)
-//   bufio.scanbytes  (s: *scanner, delim: u8)
-//                    ([]u8 | io.eof | io.error | overflow)
-//   bufio.scanrune   (s: *scanner)
-//                    (rune | io.eof | io.error | utf8.invalid | overflow)
-//   bufio.scanline   (s: *scanner) (str | io.eof | io.error | overflow)
-//
-//   bufio.init       (src: io.stream, rbuf: []u8, wbuf: []u8) stream
-//   bufio.flush      (b: *stream) (void | io.error)
-//   bufio.setflush   (b: *stream, bs: []u8) void
-//   bufio.unread     (b: *stream, buf: []u8) void
-//   bufio.isbuffered (s: io.stream) bool
-//
 // VALUE-RETURN (Hare ref/hare/bufio/stream.ha:69 init, scanner.ha:92
 // newscanner_buf): each constructor builds in a local `let r: T;`,
 // field-assigns every slot, and `return r;`. The caller owns the