Return every JSON-Schema document owned by the authenticated customer (filtered
        by `customerRef = <auth-principal>`). Excludes global schemas — those are
        returned by a separate global-list endpoint that lives outside the MCP surface.
        Each entry is a lightweight `SchemaListDTO` (id, name, type, version) — enough
        to build a picker UI or to feed an agent's "which schema should I use?" decision.
        For the full schema content (the JSON-Schema document itself) call the
        schema-by-id endpoint with the `id` from this list.

        **Not paginated** — returns the full flat set in one call. This is fine for the
        legacy per-(type, version) schemas this endpoint was built for, but be aware of
        the CUSTOM-type caveat below before using it as a CUSTOM schema picker.

        **CUSTOM-type caveat:** this endpoint lists one row PER VERSION document, not one
        row per schema group. A CUSTOM group with 5 saved versions shows up here as 5
        separate rows, all sharing the same `groupId` but different `id`/`version`. To
        discover "what custom schema groups does this customer have" (one row per group,
        with the group's current `latestPublishedVersion`), call
        scrapewise_list_custom_schema_groups instead — that is the cursor-paginated,
        one-row-per-group summary and the intended picker source for CUSTOM. Use this
        endpoint's `groupId` field only to know which group a given version row belongs to
        (e.g. after finding a version's `id` you want to add a sibling version to).

        Args:
          - none — the authenticated customer scope is implicit.

        Returns:
          `List<SchemaListDTO>` — zero or more schemas. Each row carries:
            - id (string): MongoDB ObjectId; use to fetch full content or to attach
              this schema to a new AI_CONF scraper
            - name / type / version: enough context for picker UIs and agent
              decision-making
            - groupId (string, CUSTOM-only, null otherwise): the schema group this
              version belongs to. Pass it as `body.groupId` on
              scrapewise_create_customer_schema to add a new version to this same group.

        Examples:
          - Use when: "what schemas do I have?" (non-CUSTOM, or you need per-version
            detail) — single read, returns the full inventory
          - Use when: discovering whether a customer schema for a given domain
            already exists before creating a new one via scrapewise_create_customer_schema
          - Don't use when: you want a one-row-per-CUSTOM-group summary (with
            `latestPublishedVersion`, `versionCount`, `scraperRefCount`) → use
            scrapewise_list_custom_schema_groups instead
          - Don't use when: you want global schemas too → use the global-schema-list
            endpoint (currently outside the MCP surface; see scraper-api OpenAPI for
            administrative tooling)
          - Don't use when: you need the full JSON-Schema content — this is a
            summary list; fetch by id for the full document

        Error Handling:
          - 200 with empty list if the customer has no custom schemas (not an error).
          - 401 Unauthorized if no Firebase JWT or API key.
          - 500 INTERNAL with `correlationId` if Mongo lookup fails.