Drop stale invercargill-json build and consumer dependency

Astralis uses json-glib directly but never the InvercargillJson
namespace: no source or example references it, the generated
astralis-0.1.vapi and gir contain zero references, and the linker
already drops the unused -linvercargill-json the meson dependency
injected (libastralis-0.1.so has no libinvercargill-json NEEDED
entry). The dependency was nevertheless wired into the shared
library, the exported astralis_dep, and the shipped
astralis-0.1.deps, forcing every consumer to have
invercargill-json's vapi installed for no benefit. Removed the
declaration, both wirings, the .deps entry, and the
pc:invercargill-json.pc MANIFEST build dep so the manifest
matches what the build actually requires.

Verified: clean meson build green including all 17 examples
(proving consumers of the pruned astralis_dep compile fine) with
an identical NEEDED set; meson test exits 0 (no tests defined);
usm manifest validate green; usm manifest test green. A fresh
consumer compiles with valac --pkg astralis-0.1 against the
pruned .deps chain. An unrelated pre-existing quirk was noticed:
a trivial consumer constructing WebApplication segfaults at
runtime, identically on the pre-prune baseline, so it is not
caused by this change.

MANIFEST.usm

@@ -44,7 +44,6 @@
       "pc:libxml-2.0.pc",
       "pc:libmicrohttpd.pc",
       "pc:invercargill-1.pc",
-      "pc:invercargill-json.pc",
       "pc:inversion-0.1.pc"
     ],
     "manage": [

meson.build

@@ -11,7 +11,6 @@ mhd_dep = dependency('libmicrohttpd')
 invercargill_dep = dependency('invercargill-1')
 inversion_dep = dependency('inversion-0.1')
 json_glib_dep = dependency('json-glib-1.0')
-invercargill_json_dep = dependency('invercargill-json')
 zlib_dep = dependency('zlib')
 brotli_dep = dependency('libbrotlienc')
 zstd_dep = dependency('libzstd')

src/meson.build

@@ -39,7 +39,7 @@ sources = files(
 library_version = meson.project_version()
 libastralis = shared_library('astralis-@0@'.format(library_version),
     sources,
-    dependencies: [glib_dep, gobject_dep, mhd_dep, gio_dep, gio_unix_dep, invercargill_dep, invercargill_json_dep, json_glib_dep, zlib_dep, brotli_dep, zstd_dep, inversion_dep, libxml_dep],
+    dependencies: [glib_dep, gobject_dep, mhd_dep, gio_dep, gio_unix_dep, invercargill_dep, json_glib_dep, zlib_dep, brotli_dep, zstd_dep, inversion_dep, libxml_dep],
     install: true,
     vala_gir: 'astralis-@0@.gir'.format(library_version),
     install_dir: [true, true, true, true]
@@ -77,5 +77,5 @@ install_data(
 astralis_dep = declare_dependency(
     link_with: libastralis,
     include_directories: include_directories('.'),
-    dependencies: [glib_dep, gobject_dep, invercargill_dep, invercargill_json_dep, mhd_dep, json_glib_dep, brotli_dep, zstd_dep, inversion_dep, libxml_dep] # Users of astralis need glib, gobject, invercargill, mhd, brotli, and zstd
+    dependencies: [glib_dep, gobject_dep, invercargill_dep, mhd_dep, json_glib_dep, brotli_dep, zstd_dep, inversion_dep, libxml_dep] # Users of astralis need glib, gobject, invercargill, mhd, brotli, and zstd
 )

vapi/astralis-0.1.deps

@@ -2,7 +2,6 @@ glib-2.0
 gobject-2.0
 gio-2.0
 invercargill-1
-invercargill-json
 json-glib-1.0
 inversion-0.1
 libxml-2.0