feat(kb-gates): one work log per bundle, and the quarantine is not bundle content

The bundle had two work logs. `core/log.md` was created "for tracking core directory
modifications" and holds two entries of pure migration bookkeeping (file moved,
directory created, log created) — every one recoverable from `git log` — plus a date
for the OKF conversion (2026-07-15) that matches neither the bundle log (2026-01-15)
nor git history, where the OKF rebuild lands 2026-08-28. `core/index.md` was still
linking it, which is exactly how a stale page stays in circulation. kb-lint now reports
any `log.md` that is not the bundle root's; the page moved to omp-docs/core/.AGENTTRASH/
per the trash convention, and the core index points one level up.

Both gates also walked `.AGENTTRASH/`, so trashing a page turned them red: kb-lint
demanded frontmatter from a quarantined page and kb-coverage demanded an index for the
trash directory. A gate that only goes green once the quarantined copy is deleted is a
gate that deletes history, so both skip any path containing `.AGENTTRASH` — pinned by a
test in each suite, and kb-coverage finally gets its own test file.

scripts/kb-lint.sh

@@ -12,7 +12,15 @@ from pathlib import Path
 kb = Path(sys.argv[1])
 violations = []
 
-for p in sorted(kb.rglob("*.md")):
+def pages():
+    """Markdown pages that belong to the bundle. `.AGENTTRASH/` is a quarantine, not
+    content: linting a deleted-but-not-yet-pruned page would demand its destruction to
+    make the gate go green, which is the wrong incentive."""
+    for p in kb.rglob("*.md"):
+        if ".AGENTTRASH" not in p.parts:
+            yield p
+
+for p in pages():
     rel = p.relative_to(kb)
     text = p.read_text(errors="replace")
     lines = text.splitlines()
@@ -38,9 +46,21 @@ for p in sorted(kb.rglob("*.md")):
     if not isinstance(fm, dict) or not str(fm.get("type", "")).strip():
         violations.append(f"{rel}: frontmatter lacks required 'type:'")
 
+
+# One work log per bundle, at the bundle root. A `log.md` is a reserved name, but
+# reserved does not mean "allowed in every directory": per-directory logs are how a
+# bundle ends up with fifty of them, the entry never where the next agent looks, and
+# each copy dating the same event differently. A bundle with no log at all is left to
+# the maintenance page to nag about; this gate's job is sprawl.
+logs = sorted(str(p.relative_to(kb)) for p in pages() if p.name == "log.md")
+if len(logs) > 1 or (logs and logs[0] != "log.md"):
+    violations.append(
+        "a bundle has one work log, log.md, at the bundle root; found: " + ", ".join(logs)
+    )
+
 # link integrity: fenced code blocks hold example paths, not live links — strip first.
 # Vendored spec is exempt: its example paths are illustrations, not live links.
-for p in sorted(kb.rglob("*.md")):
+for p in pages():
     if str(p.relative_to(kb)) == "references/okf-spec.md":
         continue
     text = re.sub(r"^```[^\n]*$^```[^\n]*$", "", p.read_text(errors="replace"), flags=re.M)