feat(egress-proxy-block): single-route input + merge-on-apply

Instead of asking the agent to compose and submit a full routes
file, the tool now takes ONE proposed route — host + optional
path_allowlist + optional auth — and the supervisor merges it
into the live routes table at approval time. The agent no longer
needs to fetch / reproduce / extend the existing allowlist; it
just describes the host it wants reachable.

Tool input (new):
  - `host` (required)
  - `path_allowlist` (optional, array of absolute path prefixes)
  - `auth` (optional, {scheme, token_ref})
  - `justification` (required)

Merge semantics (in `egress_proxy_apply._merge_single_route`):
  - Host NOT in current routes → append the proposed route as a
    new entry. If `auth` is set, assign the next EGRESS_PROXY_TOKEN_N
    slot.
  - Host already present → union the proposed `path_allowlist`
    with the existing one (proposed entries appended after
    existing, deduped). Existing `auth_scheme` / `token_env`
    preserved; proposed `auth` ignored (operator-controlled, not
    agent-controlled).
  - Hostname comparison is case-insensitive.

Dashboard wiring: `approve()` on an egress-proxy-block proposal
now calls `add_route(slug, proposed_route_json)` instead of
`apply_routes_change(slug, full_file)`. add_route fetches the
current routes from the running egress-proxy, merges, and calls
apply_routes_change with the merged content — so the
pipelock-mirror + SIGHUP plumbing from chunk 3 still runs
end-to-end. Audit diff still captures the full-file before/after.

Tool description rewritten to make the new shape obvious and to
stop pointing the agent at the routes file. The
`list-egress-proxy-routes` tool stays available for agents that
want to see what's currently allowed.

Tests: 9 new `_merge_single_route` cases (host absent/present,
path-allowlist union+dedup, auth-slot indexing, case-insensitive
match, existing-auth preservation, missing-host rejection,
malformed-current rejection). 407 unit + integration pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/unit/test_supervise_server.py

@@ -45,22 +45,6 @@ from claude_bottle.supervise_server import (
 
 
 class TestValidation(unittest.TestCase):
-    def test_egress_proxy_block_requires_valid_json(self):
-        with self.assertRaises(_RpcError) as cm:
-            validate_proposed_file(_sv.TOOL_EGRESS_PROXY_BLOCK, "{not json")
-        self.assertEqual(ERR_INVALID_PARAMS, cm.exception.code)
-        self.assertIn("not valid JSON", cm.exception.message)
-
-    def test_egress_proxy_block_requires_routes_array(self):
-        with self.assertRaises(_RpcError):
-            validate_proposed_file(_sv.TOOL_EGRESS_PROXY_BLOCK, '{"other": []}')
-
-    def test_egress_proxy_block_accepts_valid_routes(self):
-        validate_proposed_file(
-            _sv.TOOL_EGRESS_PROXY_BLOCK,
-            '{"routes": [{"path": "/x/", "upstream": "https://example.com"}]}',
-        )
-
     def test_pipelock_block_accepts_https_url(self):
         validate_proposed_file(
             _sv.TOOL_PIPELOCK_BLOCK,
@@ -89,8 +73,12 @@ class TestValidation(unittest.TestCase):
             "FROM python:3.13\nRUN apk add git\n",
         )
 
-    def test_empty_proposed_file_rejected_for_all_tools(self):
-        for tool in _sv.TOOLS:
+    def test_empty_proposed_file_rejected_for_tools_with_file_field(self):
+        # egress-proxy-block has structured input (validated in
+        # _validate_and_bundle_egress_route, not here) and
+        # list-egress-proxy-routes takes no input. Only the other
+        # two go through `validate_proposed_file`.
+        for tool in (_sv.TOOL_PIPELOCK_BLOCK, _sv.TOOL_CAPABILITY_BLOCK):
             with self.subTest(tool=tool):
                 with self.assertRaises(_RpcError):
                     validate_proposed_file(tool, "   \n\t")
@@ -243,7 +231,7 @@ class TestHandleToolsCall(unittest.TestCase):
                 {
                     "name": _sv.TOOL_EGRESS_PROXY_BLOCK,
                     "arguments": {
-                        "routes": '{"routes": []}',
+                        "host": "example.com",
                         "justification": "need a route",
                     },
                 },
@@ -286,7 +274,7 @@ class TestHandleToolsCall(unittest.TestCase):
             handle_tools_call(
                 {
                     "name": _sv.TOOL_EGRESS_PROXY_BLOCK,
-                    "arguments": {"routes": '{"routes": []}'},
+                    "arguments": {"host": "example.com"},
                 },
                 self.config,
             )
@@ -298,7 +286,7 @@ class TestHandleToolsCall(unittest.TestCase):
                 {
                     "name": _sv.TOOL_EGRESS_PROXY_BLOCK,
                     "arguments": {
-                        "routes": '{"routes": []}',
+                        "host": "example.com",
                         "justification": "x",
                     },
                 },