[build] Update to Bazel 7.6.0, clean up workerd_capnp usage

Author: fhanau

.bazelversion

@@ -1 +1 @@
-7.5.0
+7.6.0

src/workerd/api/BUILD.bazel

@@ -95,7 +95,6 @@ wd_cc_library(
         "modules.h",
         "rtti.h",
         "//src/pyodide:generated/pyodide_extra.capnp.h",
-        "//src/workerd/server:workerd.capnp.h",
     ],
     visibility = ["//visibility:public"],
     deps = [
@@ -111,7 +110,6 @@ wd_cc_library(
         "//src/workerd/api/node",
         "//src/workerd/io",
         "//src/workerd/jsg:rtti",
-        "//src/workerd/server:workerd_capnp",
     ],
 )
 

src/workerd/server/BUILD.bazel

@@ -146,7 +146,18 @@ wd_cc_library(
     ],
 )
 
-wd_capnp_library(src = "workerd.capnp")
+wd_capnp_library(
+    src = "workerd.capnp",
+    # Limit visibility to avoid accidental usage – there should be no need to use this outside of
+    # test-fixture and the workerd binary.
+    # TODO(cleanup): Resolve exception for api/pyodide by moving affected pyodide code into server
+    # target. This will allow downstream to not depend on workerd.capnp.
+    visibility = [
+        ":__pkg__",
+        "//src/workerd/api:__pkg__",
+        "//src/workerd/tests:__pkg__",
+    ],
+)
 
 wd_capnp_library(
     src = "workerd-meta.capnp",