docs: clean up orphaned docs and add session event types

Delete orphaned docs not in docs.json navigation (gigacode.mdx,
foundry-self-hosting.mdx, session-transcript-schema.mdx, pi-support-plan.md).
Remove outdated musl/glibc troubleshooting section. Add event types
documentation with example payloads to agent-sessions.mdx.

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

docs/docs.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://mintlify.com/docs.json",
-  "theme": "willow",
+  "theme": "mint",
   "name": "Sandbox Agent SDK",
   "appearance": {
     "default": "dark",
@@ -25,11 +25,6 @@
   },
   "navbar": {
     "links": [
-      {
-        "label": "Gigacode",
-        "icon": "terminal",
-        "href": "https://github.com/rivet-dev/sandbox-agent/tree/main/gigacode"
-      },
       {
         "label": "Discord",
         "icon": "discord",
@@ -90,13 +85,10 @@
             "group": "System",
             "pages": ["file-system", "processes", "computer-use", "common-software"]
           },
-          {
-            "group": "Orchestration",
-            "pages": ["orchestration-architecture", "session-persistence", "observability", "multiplayer", "security"]
-          },
           {
             "group": "Reference",
             "pages": [
+              "troubleshooting",
               "architecture",
               "cli",
               "inspector",
@@ -129,5 +121,10 @@
       }
     ]
   },
-  "styles": ["/theme.css"]
+  "__removed": [
+	  {
+		"group": "Orchestration",
+		"pages": ["orchestration-architecture", "session-persistence", "observability", "multiplayer", "security"]
+	  }
+  ]
 }