CL-8990: fix MCP HTTP auth recovery ignoring abort on callBlocks

[TheGreatAxios]

Cancelling an MCP tool call during HTTP auth recovery left the block-path waiter parked: callBlocks built a decoy {...authContext, signal} spread (HTTPAuthContext has no signal field) and omitted the third signal arg to withHTTPAuthorizationRecovery, so cancel never reached awaitRecovery.

Fix mirrors call: pass authContext unchanged plus signal as the third arg; the spread is deleted. No shared-machinery changes (per-waiter abort was already isolated; completeVerifiedRecovery already defers to waiters===0).

Tests (red-then-green in src/mcp/client-auth-reauth-cap.test.ts):

• block-path clone of the shared-recovery abort test: two concurrent 401s, abort waiter 1 rejects "caller stopped", waiter 2 resolves, single waitForCode/finishAuth/authURL
• block-path clone of the background-notify test: aborted waiter rejects, background finishAuth still fires onAuthorized
• plugin-level test (src/mcp/plugin.test.ts): parked block-path call aborted mid-recovery surfaces {isError: true} with the abort reason instead of hanging

Verification:

• bun run typecheck: exit 0
• bun test src/mcp/client-auth-reauth-cap.test.ts src/mcp/plugin.test.ts src/mcp/client-auth-policy.test.ts: 43 pass, 0 fail, exit 0
• bun run lint: exit 0
• bun run build: exit 0

Fixes CL-8990

[linear-code]

CL-8990