refactor: flatten CaidoCapability into direct wiring

The custom ``Capability`` subclass was 207 LoC bundling four tiny
concerns (env-var injection, tool exposure, system-prompt block,
healthcheck) — and three of them were dead code: the SDK's
``SandboxRunConfig`` doesn't accept capabilities, so
``process_manifest``, ``tools()``, and ``instructions()`` were never
called. Only ``bind()`` ran, because we invoked it manually.

Replace each piece with the obvious direct equivalent:

- **Env vars**: inject ``http_proxy`` / ``https_proxy`` / ``ALL_PROXY``
  directly into the manifest in ``session_manager.create_or_reuse``.
  This *also fixes a latent bug* — the proxy env vars in
  ``CaidoCapability.process_manifest`` weren't being applied to live
  containers, so shelled-out HTTP traffic from terminal/python tools
  wasn't actually flowing through Caido.
- **Tool exposure**: add the seven Caido tools (``list_requests``,
  ``view_request``, ``send_request``, ``repeat_request``,
  ``scope_rules``, ``list_sitemap``, ``view_sitemap_entry``) to
  ``_BASE_TOOLS`` in ``agents/factory.py`` like every other sandbox
  tool. They were already defined in ``tools/proxy/tools.py``.
- **Healthcheck**: ``entry.py`` now ``await``s
  ``wait_for_http_ready`` + ``wait_for_tcp_ready`` inline after
  ``session_manager.create_or_reuse`` returns, before any agent runs.
  No more capability state, ``configure_host_ports`` plumbing, or
  ``on_agent_start`` await-the-task indirection.
- **Instructions block**: dropped. The seven proxy tools' docstrings
  cover the HTTPQL syntax and usage already; the duplicate prompt
  fragment was overhead.

Cascade cleanups:
- Drop ``caido_capability`` from the agent context (was passed to
  every ``make_agent_context`` call but only used by the now-deleted
  ``on_agent_start`` await).
- Strip the capability await branch from
  ``StrixOrchestrationHooks.on_agent_start``; that hook now does only
  the ``tracer.agents`` mirroring it always should have.
- Drop the ``capability`` key from the session bundle.
- Drop ``strix/sandbox/caido_capability.py`` — entire file (207 LoC).
- Drop the per-file ruff ignore for the deleted file.

mypy clean on every touched file. Net -217 LoC.

strix/agents/factory.py

@@ -1,8 +1,7 @@
 """``build_strix_agent`` — assemble an ``agents.Agent`` for root or child.
 
-Wires the SDK function tools, multi-agent graph tools,
-``CaidoCapability``, and the rendered Jinja prompt into one
-``agents.Agent`` ready for ``Runner.run``.
+Wires the SDK function tools, multi-agent graph tools, and the rendered
+Jinja prompt into one ``agents.Agent`` ready for ``Runner.run``.
 
 Two flavors:
 
@@ -13,9 +12,8 @@ Two flavors:
   there — without ``stop_at_tool_names`` the SDK loop would keep
   running to ``max_turns`` even after the child reported back.
 
-Caido tools come from ``CaidoCapability.tools()`` via the SDK's
-capability merge — we don't list them here. Skills are baked into the
-system prompt at scan bring-up; there's no runtime skill-loading tool.
+Skills are baked into the system prompt at scan bring-up; there's no
+runtime skill-loading tool.
 """
 
 from __future__ import annotations
@@ -50,6 +48,15 @@ from strix.tools.notes.tools import (
     list_notes,
     update_note,
 )
+from strix.tools.proxy.tools import (
+    list_requests,
+    list_sitemap,
+    repeat_request,
+    scope_rules,
+    send_request,
+    view_request,
+    view_sitemap_entry,
+)
 from strix.tools.python.tool import python_action
 from strix.tools.reporting.tool import create_vulnerability_report
 from strix.tools.terminal.tool import terminal_execute
@@ -68,9 +75,7 @@ from strix.tools.web_search.tool import web_search
 logger = logging.getLogger(__name__)
 
 
-# Tools every Strix agent has, root or child. The Caido proxy tools
-# (list_requests, view_request, send_request, ...) are NOT here —
-# CaidoCapability.tools() returns them and the SDK merges them in.
+# Tools every Strix agent has, root or child.
 _BASE_TOOLS: tuple[Tool, ...] = (
     # Thinking + planning
     think,
@@ -101,6 +106,14 @@ _BASE_TOOLS: tuple[Tool, ...] = (
     browser_action,
     terminal_execute,
     python_action,
+    # Caido HTTP/HTTPS proxy
+    list_requests,
+    view_request,
+    send_request,
+    repeat_request,
+    scope_rules,
+    list_sitemap,
+    view_sitemap_entry,
     # Multi-agent graph tools (the bus is in ctx.context)
     view_agent_graph,
     agent_status,