feat(code,claw): the rhema mcp route, frontend wiring, disabled persistence

The spec's §10 consumer steps land. The rhema binary routes `mcp`
and everything unrecognized (the external subcommand, which is the
road the init file's stubs take: `rhema __server <name> ...`) to
rhema_mcp::cli::run, whose exit code owns the process; outside a
wired shell it exits 4 silently, exactly the spec's contract. The
claw gains its first subcommand the same way (`claw mcp ...`).

The frontends wire: session_agent_config (the TUI's three call
sites) and the headless one-shot merge the wiring's shell_env into
the agent config and the lines into the prompt's mcp section --
always behind the sandbox gate, so a session whose bash runs
elsewhere advertises nothing it cannot run. The registry keys by
profile name: a profile switch rewires, staying put reuses the
bridge and its already-spawned servers. The bridge itself moved to
a dedicated thread with its own runtime in this pass, which is what
makes wire() synchronous -- a dedicated runtime dropped at return
took the accept loop with it the first time, and a blocking CLI read
starving a current-thread runtime taught the same lesson from the
other side.

Muting persists: disabled_mcp_servers lands beside skills_disabled
in the config file, the settings toggle writes both the live set and
the config through save_config, and the running agent rebuilds so
the very next turn sees the change -- the MCP twin of the skill
toggle, with the round-trip test extended to assert the config.

The process-level pin the spec's §9 asked for: a bash child sources
the provisioned init file from BASH_ENV, calls the generated
function, the stub execs the CLI bin (the same dispatch the rhema
binary routes to), and the envelope prints -- plus the unknown-tool
path exiting 2 through clap's own text. provision and wire grow
provision_with_bin/wire_with_bin test seams so the exec chain can
run without building the frontend; the standalone rhema-mcp-cli
bin target is the seam's exec side.

crates/rhema-claw/Cargo.toml

@@ -76,6 +76,7 @@ time = { version = "0.3", default-features = false, features = ["parsing"] }
 # Inbound chat images ride base64; the dispatch decodes them into the
 # attachment store
 base64 = "0.22"
+rhema-mcp = { version = "0.1.0", path = "../rhema-mcp" }
 
 [dev-dependencies]
 tempfile = "3"