Harness spec 3.0.0-draft: the file system as a contract

filesystem.md: paths, the node kinds dir/file/mount, the access levels
none/ro/stage/commit with grants and floors, the exact error texts, and the
rule that a granted path under one that is not is reached only by its full
path. Listings, search, indexing by tokens (480 a piece, 64 repeated),
instruction files stacked from the boundary to the start directory, skills,
and memory kept by the server for both sides. Conformance areas fs_access,
instructions and chunk_tokens, answered from a reference model of the rules.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

harness/conformance/chunk.json

@@ -1,5 +1,5 @@
 {
-  "about": "Text → the pieces a knowledge document is cut into for search: about `size` characters (raised to 200 when smaller), cut just after a paragraph break, else a line break, else a sentence's \". \", found in the window's last third, with `overlap` characters (at most half the size) repeated; CRLF read as LF; pieces under 40 characters dropped.",
+  "about": "Text → the pieces a knowledge document is cut into for search: about `size` characters (raised to 200 when smaller), cut just after a paragraph break, else a line break, else a sentence's \". \", found in the window's last third, with `overlap` characters (at most half the size) repeated; CRLF read as LF; pieces under 40 characters dropped. Spec 3.0.0: indexing for search cuts by tokens instead (chunk_tokens.json, filesystem.md); this character splitter stays the rule wherever a piece is still measured in characters.",
   "cases": [
     {
       "size": 200,