Versioned alignment-layer JSON contract + thin CLI/service wrapper (adapter surface)

[bsesic]

Summary

Define a versioned alignment-layer JSON contract and ship a thin CLI / service wrapper
so TRACE can be consumed as a swappable adapter by an external platform (e.g. a postgres /
Django / Node scholarly-editions platform à la qumran-digital) without importing the Python
package. Smallest, highest-leverage item for the platform integration use case.

Motivation

TRACE round-trips its own Pydantic result models to JSON, but it is library-only — no CLI, no
service surface. The target platform architecture treats each processing step (OCR, chunking,
alignment, reuse) as an adapter behind a stable, versioned JSON contract over an immutable,
character-addressable base text, with provenance (which adapter + version produced each layer)
as a first-class field. For TRACE to be the alignment adapter, two things are needed:

1. a published, versioned alignment-layer schema (standoff: references to base-text
   offsets, matches with reason tags, witness/segment identifiers, trace_version +
   language_pack_version) — decoupled from internal model churn; and
2. a thin invocation surface (CLI reading stdin/files, emitting the contract JSON) so a
   non-Python platform can shell out or call a small service.

Scope

• Schema: a documented JSON Schema for the alignment layer (pairwise and multi-witness),
  explicitly standoff (offsets into a referenced base text, not embedded text), carrying
  per-match reason tags and full provenance/version stamps. Version the schema independently of
  the package version.
• CLI: tracealign console entry point — at minimum align and align-multi subcommands
  reading token/text input and emitting contract JSON; --lang, config flags, --version.
• Round-trip + validation: loaders that validate input against the schema and fail loudly on
  drift.
• Out of scope: a long-running HTTP server (note it as a possible follow-up; CLI is enough to be
  a subprocess adapter).

Acceptance criteria

• Published JSON Schema file in-repo, versioned, with docs and at least one golden example per layer.
• tracealign CLI entry point in pyproject.toml; tracealign align ... and align-multi ... emit schema-valid JSON.
• Output is standoff (offsets reference a base text; text not duplicated into the alignment layer) and carries adapter/version provenance.
• Schema-validation tests; CLI smoke tests; existing JSON round-trip still passes.
• TDD; suite green on 3.10/3.11/3.12; flake8 clean.

Roadmap: enabling infrastructure for downstream platform integration (qumran-digital-style);
unblocks TRACE-as-adapter independent of later linguistic stages.