Mostly cleanup spread across the package:
- Extract a generic `WebSocketTransport.json` from the inline OpenAI Responses
WebSocket transport so the same shape can be reused for other providers.
WebSocket open path now also responds to scope abort.
- Drop the `RouteContext` / `TransportContext` wrappers; the only field was
`request`, so transports and routes now take `LLMRequest` directly.
- Tighten registry semantics: registering a duplicate route id throws instead
of silently keeping the first.
- Bedrock media: dispatch by MIME table so unknown formats fail with a clear
error instead of degrading into a malformed document block.
- Anthropic Messages: refactor `step` from one long if-chain into named
per-event handlers (`onMessageStart`, `onContentBlockStart`, etc.) dispatched
from a small top-level switch. Also rename the one-off `anthropicString`
accessor to `signatureFromMetadata`.
- Executor: consolidate the duplicated sensitive-name regexes into a single
`SENSITIVE_NAME_SOURCE` plus named JSON/query field patterns.
Kit Langton
1a77519a23