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.

e2e/README.md

@@ -6,7 +6,7 @@ running `bridged` daemon**, captures the full transcript, and grades the channel
 
 This is the committed form of the ad-hoc channel test that discovered the CB-115 gaps
 (herdr `unknown` misclassification wedging delivery, dirty completion scrapes, and workers
-never calling `bridge_reply` in conversation). Run it after any change to the injector,
+never calling `fleet_reply` in conversation). Run it after any change to the injector,
 status handling, completion/failure paths, or the worker reply charter.
 
 ## What it exercises
@@ -28,7 +28,7 @@ sequenceDiagram
         T->>B: POST /sessions/{id}/message {wait:false}
         B-->>T: ticket
         B->>W: inject prompt (status-gated)
-        W-->>B: bridge_reply
+        W-->>B: fleet_reply
         T->>B: GET /tasks/{ticket}  (poll)
         B-->>T: done + reply
     end
@@ -68,7 +68,7 @@ Per-turn grade:
 
 | Grade      | Meaning                                                              |
 |------------|---------------------------------------------------------------------|
-| `OK`       | delivered and resolved by an explicit `bridge_reply` (`source=reply`) |
+| `OK`       | delivered and resolved by an explicit `fleet_reply` (`source=reply`) |
 | `DEGRADED` | delivered and answered, but resolved via completion-scrape fallback |
 | `EMPTY`    | turn completed but the reply was empty                              |
 | `FAILED`   | the worker's turn ended in failure (`phase=failed`)                 |