feat(errors): register GUARD_STEP_UP_MIN_AGE_ANCHOR condition codes

[pyramation]

Summary

Registers the two codes raised by the new anchor_conditions form of the step-up guard (constructive-io/constructive-db#3765, follow-up noted on constructive-io/constructive-planning#2055):

• GUARD_STEP_UP_MIN_AGE_ANCHOR_FK_FIELD_CONDITIONS_CONFLICT (403) — min_age_anchor given both fk_col and anchor_conditions
• GUARD_STEP_UP_MIN_AGE_ANCHOR_CONDITION_FIELD_NOT_FOUND (404) — an anchor condition references a column the anchor table lacks

Both entries are what audit-db-errors.py produces against current constructive-db main; registry.generated.ts is regenerated from the inventory (799 → 801).

Deliberately not a full inventory regen. A full audit-db-errors.py run also drops the seven STORAGE_* lifecycle codes added in ecf19ca — those have no source in constructive-db yet (pre-registered ahead of the storage lifecycle SQL) and storage-lifecycle.test.ts asserts they stay in the inventory. Only the two new entries were merged in so that work is left intact.

Link to Devin session: https://app.devin.ai/sessions/161aafecdcac47119f0a61dc759bb3eb
Open in Devin Desktop: https://app.devin.ai/desktop/session/161aafecdcac47119f0a61dc759bb3eb?variant=devin
Requested by: @pyramation

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[tenki-reviewer]

Review complete. No issues found — approved ✅.

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This PR updates the database-error inventory registry with two newly encountered PG error codes from constructive-db, plus a trailing-newline cleanup. The change is entirely data: no source logic, generated registry, or scripts are modified.

Files	Change
packages/errors/scripts/db-error-inventory.json	Adds two guard_step_up_min_age_anchor error entries with class: "public" metadata and fixes the missing trailing newline.

All scanned lenses (api-data, holistic, sweep) found no defects; the entries are consistent with the existing registry structure and the generated registry.generated.ts.

_{Reviewed commit: 1bc15c2}