Introduce three optional per-agent config fields to bound tool-call loop
execution: `max_iterations` (default 15), `streaming_timeout` (default
120s), and `turn_timeout` (default 300s wall-clock).
- Plumb limits from agent config through `_build_agents_table` and
`_start_agent` into `MultimodalAgentMCPServer` via `request_limits`
- Apply `max_iterations` and `streaming_timeout` to `RequestParams`
- Wrap turn dispatch in `asyncio.wait_for` to enforce `turn_timeout`,
logging a warning on timeout
- Document the new fields in README
Introduce `model_capabilities.mantle` flag that installs a provider-specific
override in fast-agent's `ModelDatabase._PROVIDER_MODEL_OVERRIDES` to strip
features the AWS Bedrock Mantle endpoint rejects (beta headers, extended
thinking, task budgets, web tools, prompt caching).
Without this override, fast-agent sends default beta headers and `thinking`
parameters for modern Claude models that Mantle rejects with a misleading
404 "model does not exist" error.
Retire the per-turn bearer-token forwarding mechanism in favor of
transparent authentication via operator-configured headers in
fastagent.secrets.yaml. Agents now rely on long-lived team JWTs configured
per downstream MCP server.
Replace the token-forwarding patches with debug-only traceback-capture
wrappers around three opaque fast-agent catch-sites that previously
flattened exceptions to bare strings, making downstream transport errors
diagnosable.
Update README with authentication guidance and deprecation notice for
the retired `forward_inbound_auth: true` flag (now silently ignored).
