docs: one owner for the one-log rule, and an honest scope on the census

The one-work-log rule was written near-verbatim in four places — okf-spec,
okf-maintenance, log.md's preamble, and APPEND_SYSTEM.md. Four copies is four
authorities: each can be edited alone, and the next reader cannot tell which one the
linter implements. okf-spec.md owns it; maintenance now carries the action (collapse
a second log into the root, then re-run the linter) instead of re-arguing it; the log
page points at the rule rather than restating it. APPEND_SYSTEM keeps its imperative —
a system prompt cannot fetch a link at the moment of writing — but no longer carries
the duplicated reasoning.

`inventory/index.md` advertised "all userspace program configuration on the
workstation". The one page in that directory measures `~/.config` on blankpad: not
`~/.local/share`, not system package state, not the servers. A coverage claim that
names what was measured is the difference between a census and an alibi.

Refs #60

omp-docs/inventory/index.md

@@ -1,5 +1,7 @@
 # Inventory Index
 
-Census of all userspace program configuration on the workstation.
+Tracked-vs-box-only census of userspace configuration on blankpad. Read the scope before
+trusting coverage: these pages measure `~/.config`, not `~/.local/share`, not system package
+state, not the servers.
 
 - [home-config-census.md](home-config-census.md) — Per-file tracked-vs-box-only census of ~/.config on blankpad — the input for the dotfiles pruning/adoption session.