v1.30.0 -- channel availability (Pipe C)

"Channel availability (Pipe C)" release. A new outbound surface that publishes per-channel sellable availability to a configured HTTP sink per channel. Inventory changes are collapsed into a current-state number per (channel, SKU) and debounce-published, so a busy warehouse does not fan every stock tick out to every marketplace.

Mobile. Zero mobile/ diffs on this release. The current mobile build (version 1.29.0, versionCode 10) remains current; no new APK for v1.30.0.

Added

• Channel availability materialization (Pipe C) (#424): a new channel_availability table holds sellable quantity (on_hand - allocated, Pickable / PickableStaging bins only) per channel and SKU, with a current_version / last_version pattern marking a row dirty only when the number actually changes. A connector-publisher daemon reconciles availability against live inventory - on the integration_events_visible wake and a periodic interval - and debounce-publishes dirty rows to each channel's sink. Reading live inventory rather than replaying events, it converges to the truth even for allocation changes that emit no event (reserve-at-creation, cancel), so it never publishes a stale count. Migration 075; least-privilege sentry_publisher role; new connector-publisher compose service.
• Per-channel config + admin Channels page (#424): channels carry a delivery URL, a SKU scope (skus / categories / warehouses), a declarative transform (field rename + constant injection, for the Amazon FBA vs MFN distinction), and rate / batch / debounce knobs. CRUD under /api/admin/channels with a dispatch-time SSRF guard on the sink, pause/resume, soft-delete, and a DLQ view; a new admin Channels page mirrors the Webhooks page. Every config change writes an audit_log row.