feat(config): T-1282 — the validate domain, and a move that broke a root

reach validate content / checklist / ron / name-collisions. The three old
scripts are retired, their make targets with them.

Print statements go through the logging sink rather than a collector. The
validators emit their findings as console events as they run, so a long content
validation streams instead of going quiet and dumping at the end — the message
strings and their order are unchanged, only the destination. That also
satisfies the conformance rule forbidding print() in the package, which is what
forced the question.

validate-ron was three languages deep: bash dispatching on a flag, a Python
heredoc doing collision detection, cargo run for schema validation. Logic
embedded in a shell string cannot be imported, tested, or found by anything
that indexes Python, so it became Python; the cargo call became a guarded exec.
It also split into two verbs, because --check-name-collisions answered a
different question from the default path: whether the SET of cultures is
coherent, versus whether ONE file is well-formed.

The move broke something, quietly, which is the point of doing these one at a
time. validate-checklist computed ROOT as Path(__file__).parent.parent — the
repo root while it lived at tooling/validate-checklist, and tooling/domains
once moved. Both its schema and gauntlet paths silently repointed at nothing,
the gauntlet directory "did not exist", and it reported success having checked
zero files. Caught by running it beside the original: old exit 1, new exit 0.
Now config.repo_root(), and load_schema raises ReachError instead of calling
sys.exit, which a service must not do.

Parity on the live tree: content reproduces the original byte for byte
including its counts, name-collisions likewise. Tests pin what those runs
cannot reach — the detection path, since the repo currently has no collisions,
and the argument errors.

Two things found and left alone: validate-content FAILS on the live tree with
13 missing schemas, pre-existing and unrelated to this port; and the ticket's
claim that validate-content sits in the pre-commit hook is wrong — that hook
runs only check-fact-ids and pql decisions validate, so there was no shared
edit to coordinate.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/DEVOPS.md

@@ -238,7 +238,7 @@ make clean              # Remove build artifacts and .cache/ contents
 ### Content Validation
 
 ```bash
-make validate-content     # Validate content YAML against JSON schemas
+reach validate content    # Validate content YAML against JSON schemas
 make check-fact-ids       # Check fact_id references against knowledge catalogs
 ```