remove dissolved daemon, retire ptyc, fix golden cross-platform

Complete three overdue cleanups discovered during macOS health check:

D-56 daemon dissolution: delete bin/clide.dart, DaemonServer,
and orphaned tests (test/cli/, subprocess_test, in_process_test).
Update stale "clide --daemon" references in i18n catalogs, error
messages, editor_commands, CI scripts, and decision records.

ptyc retirement: delete ptyc/ source tree, PtySession, scm_rights.
Remove from Toolchain resolution, ToolCheck gate, backend
serialization, testmode harness, Makefile, CI, and sandbox
entitlements. PTY spawning uses NativePty (Dart FFI forkpty) since
the terminal was absorbed in-tree. D-5 amended.

Golden tests: wire the existing but never-applied clideGoldenConfig
via flutter_test_config.dart. Disable CI goldens (Skia anti-aliasing
differs between macOS/Linux even with Ahem). Keep platform-keyed
goldens only — goldens/linux/ and goldens/macos/ each run on their
own OS.

Test suite: 826 pass, 0 fail on macOS (was 829 pass, 11 fail).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/kernel/src/i18n/catalog/builtin.ipc-status_en_us.json

@@ -1,6 +1,6 @@
 {
   "connected": { "translation": "connected" },
-  "connected.hint": { "translation": "clide daemon is reachable over the local socket" },
+  "connected.hint": { "translation": "backend isolate is reachable" },
   "disconnected": { "translation": "disconnected" },
-  "disconnected.hint": { "translation": "clide daemon is not running — start it with `clide --daemon`" }
+  "disconnected.hint": { "translation": "backend isolate is not running" }
 }

lib/kernel/src/i18n/catalog/builtin.terminal_en_us.json

@@ -3,5 +3,5 @@
   "subtitle.spawning": { "translation": "spawning shell…" },
   "subtitle.exited": { "translation": "Shell exited." },
   "error.unavailable": { "translation": "Terminal unavailable" },
-  "error.daemon": { "translation": "Daemon not connected. Start `clide --daemon`." }
+  "error.daemon": { "translation": "Backend not connected." }
 }