feat(gateway): mandatory identity-token attribution on every data plane (PR #354 review)

Codex review: the /31 TAP doesn't make source IP unspoofable, and the
app-layer token was returned by launch but never delivered or enforced, so
a spoofed source could select a victim bottle's policy/tokens. Make the
token mandatory and deliver it on each attributed plane (anti-spoof landed
separately as the network boundary).

Enforcement (control plane):
- `Orchestrator.resolve` now requires a matching (source_ip, identity_token)
  pair (constant-time) — no source-IP-only fallback. `/resolve` fail-closes
  (403) on a missing/empty/mismatched token.

Delivery, per plane (the token is `token_urlsafe`, safe in a URL):
- egress: proxy credentials (`HTTPS_PROXY=http://bottle:<token>@gw`). The
  addon reads `Proxy-Authorization` — from the request (HTTP) or captured at
  the CONNECT for HTTPS tunnels (keyed by client conn, cleared on disconnect)
  — validates, and strips it (+ the legacy header) before upstream.
- git-http: a URL-scoped `http.<gate>/.extraHeader: x-bot-bottle-identity`
  in the agent's git config (only over the http transport).
- supervise: `mcp add --header x-bot-bottle-identity: <token>` (claude +
  codex); the server reads the header and passes it to resolve.

Wiring: thread `ctx.identity_token` onto the firecracker + docker plans and
into the agent env/config at launch.

Verified on a KVM host: egress with the correct proxy-cred token returns
200 (HTTP and HTTPS/CONNECT), and no-token / wrong-token return 403; a real
`cli.py start --backend=firecracker` launch provisions git config + the
supervise MCP header and reaches the agent session, all under mandatory
enforcement. Fixed a `claude mcp add` arg-order bug (--header must follow
the positional name/url) found by that launch.

Transparent proxy for tools that ignore proxy env is deferred to a
follow-up (see thread); anti-spoof + host firewall remain the fail-closed
boundary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck

bot_bottle/orchestrator/service.py

@@ -99,16 +99,18 @@ class Orchestrator:
         """Fail-closed attribution (delegates to the registry)."""
         return self.registry.attribute(source_ip, identity_token)
 
-    def resolve(self, source_ip: str, identity_token: str = "") -> BottleRecord | None:
-        """Resolve the bottle behind a request — the source-IP-keyed lookup
-        the multi-tenant gateway makes per request; the returned record
-        carries its `policy`. With a token, full attribution (source IP +
-        token); without, network-layer attribution by source IP alone
-        (valid where the IP is unspoofable and the control plane is
-        gateway-only)."""
-        if identity_token:
-            return self.registry.attribute(source_ip, identity_token)
-        return self.registry.by_source_ip(source_ip)
+    def resolve(self, source_ip: str, identity_token: str) -> BottleRecord | None:
+        """Resolve the bottle behind a request — the per-request lookup the
+        multi-tenant gateway makes; the returned record carries its `policy`.
+
+        **Mandatory pair**: requires a matching `(source_ip, identity_token)`
+        (constant-time). There is no source-IP-only fallback — the app-layer
+        token is delivered on every attributed data plane (egress proxy
+        credentials, git-gate/supervise headers), so a missing or mismatched
+        token fail-closes. This keeps a spoofed source IP (which the /31 TAP
+        alone does not prevent) from selecting another bottle's policy/tokens
+        without also holding that bottle's unguessable token."""
+        return self.registry.attribute(source_ip, identity_token)
 
     def set_policy(self, bottle_id: str, policy: str) -> bool:
         """Update a bottle's gateway policy in place (live reload). False if