Restore sitemap tools + unify proxy I/O contract

Re-add list_sitemap and view_sitemap_entry from main, ported to the
new caido-sdk-client layout via raw GraphQL queries (the typed SDK
doesn't expose sitemap operations, but the Caido server still
supports sitemapRootEntries / sitemapDescendantEntries / sitemapEntry).
Wired through caido_api (sandbox-importable helpers), the host-side
@function_tool wrappers, factory _BASE_TOOLS, the system prompt, the
python skill doc, and the public proxy docs.

While threading these through, lock down the output contract across
every proxy tool so the model sees one consistent shape:

- All tools wrap success/failure in {"success": bool, "error"?: str}
- Canonical field names: status_code, length, roundtrip_ms (omitted
  when 0), is_tls, has_descendants. snake_case everywhere on output;
  camelCase stays only on the input side where it's the GraphQL
  schema.
- repeat_request now returns a structured response that matches
  list_requests' response_summary shape (parse_raw_response parses
  the raw bytes into status_code / length / headers / body), with
  body capped at 8KB and a body_truncated flag so the model knows
  when to fetch the full body via view_request.
- RepeatRequestRenderer was reading non-existent top-level keys
  (status_code, response_time_ms, body) and silently displaying
  nothing useful — now reads the structured response shape.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/tools/proxy.mdx

@@ -66,6 +66,8 @@ asyncio.run(main())
 | `list_requests()`      | Query captured traffic with HTTPQL filters |
 | `view_request()`       | Get full request/response details          |
 | `repeat_request()`     | Replay a request with modifications        |
+| `list_sitemap()`       | Browse the request-tree view of discovered surface |
+| `view_sitemap_entry()` | Inspect one sitemap entry + its related requests |
 | `scope_rules()`        | Manage proxy scope (allowlist/denylist)    |
 
 For one-off arbitrary requests, use shell tooling like `curl` — the