* fix(mcp): propagate HERMES_HOME override onto the MCP event loop
Closes the known limit documented in #44007: tasks scheduled via
run_coroutine_threadsafe are created INSIDE the MCP loop thread, so they
copy that thread's context — a per-request profile scope (dashboard
?profile= endpoints, e.g. the MCP 'Test server' probe) silently vanished
for anything resolving get_hermes_home() inside the coroutine. Most
visible symptom: OAuth token-store paths (HERMES_HOME/mcp-tokens/)
resolved against the process home instead of the selected profile, so
testing an OAuth MCP cross-profile read the wrong tokens.
_run_on_mcp_loop now wraps scheduled coroutines with the caller's
context-local override (_wrap_with_home_override): set inside the task's
own context on the loop, reset on completion — task-local, so concurrent
calls carrying different scopes don't interfere, and the loop thread's
default context stays untouched. No-op (coroutine passes through
unwrapped) when no override is active, i.e. every non-dashboard caller.
web_server's probe comment updated from 'known limit' to 'covered'.
Tests: override propagation (direct + factory form), OAuth token-path
resolution on the loop, loop-context cleanliness after scoped calls,
no-op passthrough. 225 green across mcp_tool + unification suites.
* test(mcp): concurrent different-scope calls don't interfere
73dd584995