CB-622: rename bridge_* tool names to fleet_* in Markdown docs

Rename the eleven MCP tool names (bridge_ack/ask/list/poll/profiles/reply/
send/spawn/status/stop/whoami) to their fleet_* names across the Markdown
documentation. fleet_* is written as the normal name; one deprecation note
in README.md says bridge_* still works for one release.

docs/MCP-Contract.md is renamed only inside section 6 (lines 210-293):
sections 1-5 and 7-11 are stale pre-build design text (CB-609) and are
deliberately left with old names so dead text does not look maintained.

Also renames e2e/bridge_ask_transcript.md to e2e/fleet_ask_transcript.md
to match its content. CLAUDE.md, wiki/, plugin/skills/setup/SKILL.md and
.claude/skills/port-to-opencode/SKILL.md are owned by other units and are
untouched.

docs/MCP-Contract.md

@@ -220,17 +220,17 @@ sequenceDiagram
     participant H as herdr
     participant W as Worker (Claude)
 
-    P->>B: bridge_send("do X", target=w) — blocks
+    P->>B: fleet_send("do X", target=w) — blocks
     B->>B: register waiter(w)
     B->>H: agent.send(w, "do X")  (idle window)
     H-->>W: prompt injected
     W->>W: works the turn
-    W->>B: bridge_reply("result")
+    W->>B: fleet_reply("result")
     B->>B: resolve waiter(w)
     B-->>P: { outcome:"reply", text:"result" }
 ```
 
-### 6.2 Clarification — reverse rendezvous (`bridge_ask`)
+### 6.2 Clarification — reverse rendezvous (`fleet_ask`)
 
 The worker pauses mid-turn to ask; the primary answers; the worker resumes in the same turn.
 
@@ -240,14 +240,14 @@ sequenceDiagram
     participant B as bridged
     participant W as Worker
 
-    P->>B: bridge_send("do X", target=w) — blocks
+    P->>B: fleet_send("do X", target=w) — blocks
     B-->>W: "do X" (injected)
-    W->>B: bridge_ask("which config?") — worker blocks
+    W->>B: fleet_ask("which config?") — worker blocks
     B-->>P: { outcome:"question", text:"which config?", turn_id }
-    P->>B: bridge_send("config.yaml", target=w, turn_id) — blocks again
-    B-->>W: resolve bridge_ask → { answer:"config.yaml" }
+    P->>B: fleet_send("config.yaml", target=w, turn_id) — blocks again
+    B-->>W: resolve fleet_ask → { answer:"config.yaml" }
     W->>W: resumes same turn
-    W->>B: bridge_reply("done")
+    W->>B: fleet_reply("done")
     B-->>P: { outcome:"reply", text:"done" }
 ```
 
@@ -261,10 +261,10 @@ sequenceDiagram
     participant B as bridged
     participant W as Worker
 
-    P->>B: bridge_send("do X", target=w, block=false)
+    P->>B: fleet_send("do X", target=w, block=false)
     B-->>P: { outcome:"dispatched", dispatch_id }
     P->>P: continues its own work
-    W->>B: bridge_reply("result")
+    W->>B: fleet_reply("result")
     Note over B: no waiter → detached path
     B->>B: Injector.enqueue(primary_pane, "result")
     B-->>P: injected into idle pane (status-gated)
@@ -272,7 +272,7 @@ sequenceDiagram
 
 ### 6.4 Uncooperative worker — turn-done fallback
 
-A worker that never calls `bridge_reply` still returns a result: `bridged` reads its terminal
+A worker that never calls `fleet_reply` still returns a result: `bridged` reads its terminal
 tail when the turn completes.
 
 ```mermaid
@@ -281,9 +281,9 @@ sequenceDiagram
     participant B as bridged
     participant W as Worker
 
-    P->>B: bridge_send("do X", target=w) — blocks
+    P->>B: fleet_send("do X", target=w) — blocks
     B-->>W: "do X" (injected)
-    W->>W: works, never calls bridge_reply
+    W->>W: works, never calls fleet_reply
     B->>B: StatusPoller sees agent_status → idle/done
     B->>B: AgentControl.read(w, "recent")
     B-->>P: { outcome:"turn_done", text:<terminal tail> }