## Why

The platform currently treats `RunEndpoint` as both a durable database resource and a live runtime connection. That creates the wrong product model: Platform should behave like a registry and dispatcher, while Run should behave like an authenticated RPC worker that registers, heartbeats, and receives work only while its token-backed session is alive.

## What Changes

- **BREAKING** Remove first-party server-to-`RunEndpoint` persistence as the runtime routing model; server records no longer bind to a durable run endpoint row.
- Introduce a Redis-backed runtime session registry for Run registration, heartbeat leases, capability snapshots, capacity snapshots, and token/session lookup.
- Require development, test, and production flows to use Redis for runtime registry behavior; do not add an in-memory registry fallback for normal test execution.
- Retarget durable jobs from endpoint rows to logical server/component targets such as `serverInstanceId + componentKind + componentKey`.
- Keep platform-owned distribution builds separate from machine-side Run sessions; build routing remains a platform builder responsibility, not a registered Run endpoint capability.
- Replace user-facing run endpoint selection/status with runtime connection health derived from Redis leases and durable component/server records.

## Capabilities

### New Capabilities

- `redis-runtime-session-registry`: Redis-backed registration, heartbeat, token validation, routing, and capability snapshots for machine-side Run sessions.

### Modified Capabilities

- `platform-side-distribution-builds`: Remove requirements that bind a server instance to a generated run endpoint; preserve platform-owned builds while using runtime registration rather than durable endpoint rows.

## Impact

- `platform/`: domain types, DTOs, repositories, service scheduling, Run control registration, job claim/lease validation, server lifecycle dispatch, runtime action availability, tests, and local dev/test setup.
- `platform_web/`: server management API types, runtime connection status UI, run generation/deployment copy, and tests that currently reference run endpoints.
- `plugins/`: plugin bridge and companion-facing contracts where they expose or consume run endpoint identifiers.
- Infrastructure: Redis becomes a required dependency for dev, test, and production runtime registry behavior.