Census Filesystem.Read result migration dispositions

[gunbai-bot]

Analysis artifact only — do not merge under the quantitative-artifact policy.

This PR records a symbolic disposition for each of the 91 unconverted Filesystem.Read consumption sites on current main. It deliberately does not define the population, roster, or re-derivation machinery: extdeps.filesystem.filesystem_io filesystem_read_outcome_adoption_standing is the sole authority for those facts, and this census imports that standing as its subject.

Each row adds only the per-site policy decision: whether all read errors refuse, ENOENT alone means absence, a typed refusal survives, an unguarded read must refuse, or one failed read refuses a whole multi-read observation. The already-converted gunbc.ci_yaml_validate site and the deleted walk-plan fixture are absent, leaving exactly 91 rows.

The earlier shadow ReadError vocabulary, competing shell/perl recipe, and separate builtin census note were removed. This PR now carries no second filesystem model or population instrument.

Verification

• Merged current main, including Model filesystem read outcomes without fusing transport #9296.
• git diff origin/main contains only dag/gunbc/filesystem_read_consumer_census.dag.
• rg -c 'read_consumer\\(site:' dag/gunbc/filesystem_read_consumer_census.dag → 91.
• git diff --check — PASS.
• Pre-push cargo fmt --all --check — PASS.

[gunbai-bot]

Review 56725 is correct. The 91-row carrier has no consumer, no executable join from its NonEmptyStr identities to the actual call sites, and therefore no way to distinguish a correct disposition from a stale or contradicted one. Replacing the strings with resolved references and building a joining gate would turn this disposable quantitative artifact into a new permanent migration authority, duplicating the already-merged adoption standing rather than merely recording a snapshot. Under the operator ruling that analysis-only quantitative PRs are read and closed rather than merged, the appropriate fix is deletion by closing this PR, not growing inert census machinery until it looks mergeable. The merged filesystem_read_outcome_adoption_standing remains the sole live population authority. — sent from zesty-newt-651

[gunbai-bot]

Closing after review: this analysis artifact is not mergeable authority, and making its snapshot executable would create the parallel migration system the review correctly rejects. The live adoption standing remains on main. — sent from zesty-newt-651