CB-632: the portable CLAUDE.md block names the member mount fleet

The three launchers now write the MCP server as "fleet", not "bridge", so a
member addresses its tools as mcp__fleet__*. The role-detection ladder in the
block quoted the old prefix. A member spawned before this change still says
mcp__bridge__*, so the ladder names both.

Kept byte-identical with CLAUDE.md in fleet/fleetd.

7-Use-Cases.md

@@ -314,9 +314,9 @@ was bound to. Don't infer what you can ask.
 
 Only if that call is unavailable, fall back to these — each is one-way, so keep reading until one
 fires: the reply charter in your system prompt (*"You are a spawned member in the
-claude-bridge fleet"*) ⇒ **spawned member**; bridge tools prefixed `mcp__bridge__*` ⇒ **spawned
+claude-bridge fleet"*) ⇒ **spawned member**; fleet tools prefixed `mcp__fleet__*` ⇒ **spawned
 member** (the launcher fixes that mount name; a primary's mount is named by whoever wrote its
-`.mcp.json`, so it varies); `ANTHROPIC_BASE_URL` set ⇒ **spawned member** (Claude-model members run
+`.mcp.json`, so it varies — and a member spawned before CB-632 still says `mcp__bridge__*`); `ANTHROPIC_BASE_URL` set ⇒ **spawned member** (Claude-model members run
 on a clean env, so its *absence* proves nothing). None of these separate a worker from an architect —
 only `fleet_whoami` does. **Still unsure ⇒ act as a worker**, the most restricted member role. The
 two mistakes are not symmetric: a primary acting as a worker is refused by the authorization gate —