CB-632: ignore fleetd.yaml too, and fix the docs that named the old example

Unit 3 renamed bridged.example.yaml to fleetd.example.yaml and taught Fleetd to
read fleetd.yaml first. Two things it left behind.

bridged/.gitignore still ignored only bridged.yaml. An operator who follows the
new comment and copies the example to fleetd.yaml gets an untracked live config
holding tokens, and git offers to commit it. Both names are ignored now, because
both names work until the cutover.

Three design docs still pointed readers at bridged.example.yaml, a file that no
longer exists under that name.

docs/CB-402-OpenCode-Adapter.md

@@ -138,7 +138,7 @@ String kind          // "claude-code" (default) | "opencode"
   so the record stays declarative.)
 - Keep the existing back-compat constructors; `kind` is additive and optional.
 
-`bridged.example.yaml` documents a two-kind `workers:` block.
+`fleetd.example.yaml` documents a two-kind `workers:` block.
 
 ### C. `OpenCodeLauncher` — the adapter hooks for opencode
 
@@ -208,7 +208,7 @@ sequenceDiagram
    `ClaudeCodeLauncher` extend it with `namePrefix()="claude"` and `buildLaunch()` wrapping
    today's guard+env+argv logic. Green build, identical tests — pure refactor. *(IDE
    `refactor` where possible; the primary re-runs the gate workers can't.)*
-2. **`kind:` discriminator.** Add the field + normalization + `bridged.example.yaml`. Default
+2. **`kind:` discriminator.** Add the field + normalization + `fleetd.example.yaml`. Default
    path unchanged (`kind=claude-code`).
 3. **`OpenCodeLauncher`.** Implement the three hooks; unit-test `buildLaunch` (env has no
    `ANTHROPIC_BASE_URL`; `OPENCODE_CONFIG` points at a file carrying the bridge MCP block +