fix(newos4): memory-graph loads stop rewriting user data; unknown sizes say unknown

Three follow-ups from the merge review, each with the assertion that pins it.

module-memory-graph.js
- _normalizeEdges no longer mutates stored weights. It capped legacy 'failed' edges
  from 0.8 to 0.2 in memory, and the next debounced save made that permanent - an
  irreversible migration of the user's graph with no schema version. The cap moved to
  _effectiveWeight(), which ranking (showStats "Strongest relationships"), the session
  view and prune() now use; the stored record is left exactly as written.
- config.json is stamped version: 2 so a future format change can migrate deliberately.

ext/webdav.js
- the two fallback parsers emit size: null instead of 0. They cannot see the size
  column, and 0 rendered as "0 B" - the same "every file looks empty" symptom as the
  parseInt bug fixed in e639c2d, one regex miss away.
- _formatSize(null) renders '—' (unknown) rather than '0 B'; 0 still renders '0 B'.

module-aiassist.js
- the lock timeout now says what to do: "AI is still busy with another turn (waited Ns).
  Wait for it to finish, or run 'ai-stop' and retry - the running turn's lock is left
  alone." It used to be a dead-end string.

Tests: test-memory-graph 39 (T6.4 rewritten to the read-time contract: stored weight
stays 0.8, effective 0.2, success unaffected), test-webdav-sizes 28 (A14d null -> '—').
maintain 26/26, live v4.6.141: _effectiveWeight 0.2 with the edge object unchanged,
_formatSize(null) '—', '0 B' still '0 B'.

1 files changed, 9 insertions, 2 deletions

diff --git a/modules/ext/webdav.js b/modules/ext/webdav.js
index e78e876..c7efbf9 100644
--- a/modules/ext/webdav.js
+++ b/modules/ext/webdav.js
@@ -480,7 +480,10 @@ class WebDAVModule {
                     entries.push({
                         name: decodeURIComponent(href.replace(/\/$/, '').split('/').pop() || href),
                         type: isDir ? 'dir' : 'file',
-                        size: 0,
+                        // null, not 0: these are the fallback parsers, which cannot see the
+                        // size column. 0 rendered as "0 B", i.e. a listing that looked like
+                        // every file was empty (the bug _parseAutoindexSize fixes upstream).
+                        size: null,
                         mtime: null,
                         href: href
                     });
@@ -496,7 +499,10 @@ class WebDAVModule {
                     entries.push({
                         name: decodeURIComponent(href.replace(/\/$/, '').split('/').pop() || href),
                         type: isDir ? 'dir' : 'file',
-                        size: 0,
+                        // null, not 0: these are the fallback parsers, which cannot see the
+                        // size column. 0 rendered as "0 B", i.e. a listing that looked like
+                        // every file was empty (the bug _parseAutoindexSize fixes upstream).
+                        size: null,
                         mtime: null,
                         href: href
                     });
@@ -2479,6 +2485,7 @@ class WebDAVModule {
     }
 
     _formatSize(bytes) {
+        if (bytes === null || bytes === undefined) return '—';   // listing could not determine it
         const n = Number(bytes);
         if (!Number.isFinite(n) || n < 0) return '—';
         if (n < 1024) return n + ' B';