docs: README + example.json for cred-proxy (PRD 0010)

- Architecture diagram gains the cred-proxy lane (agent talks plain
  HTTP via bearer-auth-injection; sidecar talks HTTPS to the real
  upstream with the manifest token).
- Adds a cred-proxy entry under the sidecar bullet list, with a
  pointer to PRD 0010.
- Manifest example illustrates the `tokens` array on a bottle.
- Auth section notes that declaring an `anthropic` token routes
  CLAUDE_BOTTLE_OAUTH_TOKEN through the sidecar instead of into
  the agent's environ.
- claude-bottle.example.json gains an `agentic` bottle declaring
  all four token kinds, plus a paired `agentic-helper` agent.

claude-bottle.example.json

@@ -36,6 +36,20 @@
           "files.pythonhosted.org"
         ]
       }
+    },
+
+    "agentic": {
+      "env": {
+        "GIT_AUTHOR_NAME": "Eric Diderich",
+        "NODE_ENV":        "development"
+      },
+      "tokens": [
+        { "Kind": "anthropic", "TokenRef": "CLAUDE_BOTTLE_OAUTH_TOKEN" },
+        { "Kind": "github",    "TokenRef": "GH_PAT" },
+        { "Kind": "gitea",     "TokenRef": "GITEA_TOKEN",
+          "Url":  "https://gitea.dideric.is" },
+        { "Kind": "npm",       "TokenRef": "NPM_TOKEN" }
+      ]
     }
   },
 
@@ -52,6 +66,12 @@
       "prompt": "You help maintain Gitea-hosted projects. Prefer small, focused commits. Follow Conventional Commits. Run tests before pushing."
     },
 
+    "agentic-helper": {
+      "bottle": "agentic",
+      "skills": [],
+      "prompt": "You operate against APIs whose credentials live in a per-bottle cred-proxy sidecar. Your environ carries only proxy URLs."
+    },
+
     "minimal": {
       "bottle": "default",
       "skills": [],