Add Claude settings templates for autonomous roles (gt-6957)

- Create internal/claude package with embedded settings templates
- settings-autonomous.json: gt prime && gt mail check --inject (SessionStart)
- settings-interactive.json: gt prime only (SessionStart)

- Update witness.go: EnsureSettings before session, remove broken gt prime injection
- Update refinery/manager.go: EnsureSettings before session, remove broken NudgeSession
- Update session/manager.go: EnsureSettings for polecats, remove broken issue injection

All autonomous roles (polecat, witness, refinery) now get proper SessionStart hooks
automatically when their sessions are created. No more timing-based gt prime injection.

internal/claude/config/settings-interactive.json

@@ -0,0 +1,40 @@
+{
+  "enabledPlugins": {
+    "beads@beads-marketplace": false
+  },
+  "hooks": {
+    "SessionStart": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "gt prime"
+          }
+        ]
+      }
+    ],
+    "PreCompact": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "gt prime"
+          }
+        ]
+      }
+    ],
+    "UserPromptSubmit": [
+      {
+        "matcher": "",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "gt mail check --inject"
+          }
+        ]
+      }
+    ]
+  }
+}