Replace the spawn-time static Authorization header for OAuth-managed HTTP
MCP servers with McpOAuthClient, a custom implementation of rmcp's
StreamableHttpClient trait that resolves the bearer token on every
request via load_or_refresh_mcp_token. Tokens that expire mid-session
now refresh transparently instead of failing tool calls until restart.
On a 401 for an injected token, the wrapper force-refreshes (identity-
aware: a still-unexpired copy of the rejected token is not trusted) and
retries exactly once, matching Claude Code / official SDK semantics.
Both *_with_max_sse_event_size trait methods are overridden to preserve
the inner client's SSE size enforcement, and the inner reqwest client
mirrors rmcp's default (pool_max_idle_per_host(0), no redirects).
SSE, stdio, and static-header HTTP paths are unchanged; startup
warning semantics (McpAuthRequired reasons) are preserved. Verified
live: mid-session backdated token refreshed transparently during an
active atlassian session.
