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/CB-402-OpenCode-Adapter.md

@@ -184,7 +184,7 @@ sequenceDiagram
     participant O as OpenCodeLauncher
     participant B as HerdrPeerLauncher (base)
     participant H as herdr
-    P->>M: bridge_spawn(profile="oc-impl")
+    P->>M: fleet_spawn(profile="oc-impl")
     M->>C: spawn(SpawnRequest)
     C->>C: kind(profile)=="opencode"
     C->>O: spawn(req)
@@ -226,11 +226,11 @@ until it is "major" (Stage-B whole), per the CB-401 bar.
 - **opencode TUI ⇄ herdr injection.** herdr drives a pane by typing into a TUI. Must confirm
   opencode's TUI accepts injected keystrokes/submit the way `claude` does, and reaches an
   `injectable` status the CB-306 gate recognizes. *Validation:* spawn one opencode worker,
-  watch the readiness gate pass, `bridge_send` a trivial task.
+  watch the readiness gate pass, `fleet_send` a trivial task.
 - **Bridge MCP visibility in opencode.** Confirm `OPENCODE_CONFIG` (or `opencode mcp add`)
-  actually surfaces the `bridge_*` tools inside the opencode session, and that `bridge_reply`
+   actually surfaces the `fleet_*` tools inside the opencode session, and that `fleet_reply`
   is callable — the reply-charter is worthless if the tool isn't mounted. *Validation:* the
-  worker completes a task by calling `bridge_reply`; the reply lands via the CB-307 path.
+  worker completes a task by calling `fleet_reply`; the reply lands via the CB-307 path.
 - **opencode MCP/config schema drift.** opencode is fast-moving (1.1.31 today). Pin the config
   schema we generate against the installed version; treat the exact keys (`type: "remote"` vs
   `"http"`, `instructions` shape) as a dogfood-verified fact, not an assumption.
@@ -281,7 +281,7 @@ as a dogfood-verified fact for 1.18.5.
 | §5 risk | Result |
 |---|---|
 | opencode TUI ⇄ herdr injection; CB-306 gate | ✅ `peer pane=wD:p3 reached injectable state` ~0.6s after `agent.start` |
-| Bridge MCP visible + `bridge_reply` callable | ✅ MCP `initialize` from `Implementation[name=opencode, version=1.18.5]`; worker replied through the tool |
+| Bridge MCP visible + `fleet_reply` callable | ✅ MCP `initialize` from `Implementation[name=opencode, version=1.18.5]`; worker replied through the tool |
 | Config schema drift (1.1.31 → 1.18.5) | ✅ unchanged, see above |
 | Provider credentials | ✅ free tier, zero credentials |
 
@@ -291,7 +291,7 @@ Full lifecycle exercised through the REST surface:
    to `OpenCodeLauncher` (`spawning opencode profile=opencode-free`), pane `wD:p3`.
 2. Readiness: `{"ready":true,"status":"idle"}`, roster state `ready`.
 3. `POST /sessions/{id}/message` → **`{"replySource":"reply","reply":"391"}`** — a *structured*
-   `bridge_reply`, not the CB-115 completion-fallback transcript scrape. The clean path.
+   `fleet_reply`, not the CB-115 completion-fallback transcript scrape. The clean path.
 4. `DELETE /workers/wD:p3` → `204`, roster empty, tolerant teardown (`tab_not_found` ignored —
    opencode had already closed its own tab).