Rule 3 root extension: a ledgered cross-package prose-id leg on check-doc-authoring, sized by its own AST census (#13355)

* feat(tooling): Rule 3's root extension lands as a ledgered cross-package prose-id leg (#13297)

The #13179 deferral's own revival condition fired: the AST re-census reads
831 id-bearing string sites (974 occurrences, 231 files, 632 (file,id)
pairs) outside packages/spec — the card's grep-shaped ~11 was ~75x under.

Route: root widening over per-package guards — one criterion
(INTERNAL_ID_SOURCE), one walker, one baseline; a new package is covered on
arrival. Coverage is TOTAL over non-test string literals (the audience
question is not mechanizable from the AST; it lives in the baseline diff
where review can see it), held against scripts/doc-authoring-prose-id
.baseline.json: growth reds (strip the id or move it to a comment; baseline
entries are maintainer-only per #8435), shrink reds as stale (regenerate
with --census-ledger, which refuses to grow the file). While non-empty the
ratchet doubles as the leg's blindness floor.

--census prints the instrument's full enumeration with consumer shapes;
--census-ledger prints/refreshes the baseline. Self-test battery covers the
concatenation-split founding shape, comment/test/spec exclusions, template
determinism, the colour and cross-repo edge cases, prefilter superset, and
all three ledger verdicts. Boundary output and the dispatch-gates
declaration (packages/**) updated; check-ratchet-remedy-authority CONTROL
reclassifies this gate as marked.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KX8wnyjStaZcuMyAMNsy3N

* test(pm): dispatch-gates pins follow the #13297 root widening — packages/** is positive coverage, the spec-non-src residual is a recorded over-claim

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KX8wnyjStaZcuMyAMNsy3N

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Co-authored-by: Claude <noreply@anthropic.com>

Author: os-project-manager