fix(newos4): WebDAV listing sizes + pull, and five MemoryGraph defects

Closes STEER-20261102-205416-facd and STEER-20261102-204031-f82a.

WebDAV (modules/ext/webdav.js):
- listings showed "21 B" for a 21 KB file: nginx emits humanised sizes
  (autoindex_exact_size off, vhost :412) and _parseAutoindex did parseInt("21K").
  _parseAutoindexSize() handles K/M/G, decimals, lowercase and "-"; PROPFIND's
  exact getcontentlength path is untouched.
- webdav-pull into a missing local directory printed "Pulled: ... (N bytes)" and
  wrote nothing: it ignored fs.writeFile's false return (virtual-fs.js:561).
  It now creates the parent chain, checks the write, and only reports success
  after a confirmed write. The byte count uses TextEncoder, not .length
  (a Cyrillic file under-reported ~2x).
- _formatSize gained the GB branch the parser already accepted (3 GB printed
  "3072.0 MB") and no longer prints "NaN MB" for a missing size.

MemoryGraph (modules/core/module-memory-graph.js):
- addEdge averages weights, so every repeat pulled a strong edge toward the
  call site's constant (0.9 -> 0.7 -> 0.6). Now Math.max, with decay left to
  applyDecay(); prune() untouched.
- task ids were `task-${Date.now()}`, so re-submitting a task never deduped:
  now a hash of agent + normalised text.
- recordFileAccess no longer records the graph's own /.memory_graph/ store.
- failed tool calls were weighted 0.8 vs success 0.5, so showStats ranked
  failures as strongest: now 0.2. Legacy 0.8 failures are capped on load.
- concept ids keep punctuation ("concept:(v2!),"): slugged, and the slug uses
  \p{L}\p{N} so Cyrillic/CJK/accented text still yields nodes -- an a-z0-9 slug
  silently produced none.

Review findings folded in from the regression pass: the non-Latin regression
(a-z0-9 slug), the GB formatter asymmetry, and the pull byte count were all
found by review, not by the patch authors, and each now has a test.

Tests: test-webdav-sizes.js 27 (was RED 15/24 before the fix), test-memory-graph.js
37 (RED 17/32), both auto-discovered by newos4-maintain -- 26/26 node tests.
Live on v4.6.140: _parseAutoindexSize('21K') 21504, _formatSize -> "21.0 KB",
_formatSize(2GiB) "2.0 GB", slug Cyrillic "исправить-парсер-ошибок", 0 console errors.

0 files changed, 0 insertions, 0 deletions