fix(claude): include identity header in supervise MCP fallback recovery command

The manual registration command shown in the fallback warning when
`claude mcp add supervise` fails was missing the `--header
x-bot-bottle-identity: <token>` option. Since (source_ip,
identity_token) attribution is now mandatory on the supervise server,
the missing header caused every subsequent supervise request to fail
closed as unattributed — defeating supervision for the entire bottle.

Reuse the already-constructed `token` variable to build the same
`manual_header` string the automatic path uses; include it in the
printed command. Tests verify both the happy path and the fallback
include (or correctly omit) the header.

Addresses P2 finding in #471 (comment 7, didericis-codex 2026-07-25).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bot_bottle/contrib/claude/agent_provider.py

@@ -327,11 +327,15 @@ class ClaudeAgentProvider(AgentProvider):
             user="node",
         )
         if r.returncode != 0:
+            manual_header = (
+                f" --header {shlex.quote(f'{_IDENTITY_HEADER}: {token}')}" if token else ""
+            )
             warn(
                 f"`claude mcp add supervise` failed (exit {r.returncode}): "
                 f"{(r.stderr or r.stdout or '').strip()}. Inside the bottle, "
                 f"register manually with: "
-                f"claude mcp add --scope user --transport http supervise {supervise_url}"
+                f"claude mcp add --scope user --transport http "
+                f"supervise {supervise_url}{manual_header}"
             )
 
     def headless_prompt(self, prompt: str) -> list[str]: