feat: open useful USER_TYPE-gated features to all users (#644)

* feat: open useful USER_TYPE-gated features to all users

Remove 13 process.env.USER_TYPE === 'ant' gates that restricted useful
features to Anthropic employees. These features work without Anthropic
infrastructure and are now available to all open-build users.

Features opened:
- Agent nesting (sub-agents can spawn sub-agents)
- Effort 'max' persistence in settings
- Plan mode interview phase (controlled by feature flags)
- Sandbox disabled commands (via ~/.claude/feature-flags.json)
- All tips visible to all users (plan mode, feedback, shift-tab)

Simplified:
- Fullscreen defaults to off (use /config to enable)
- Explore agent always uses haiku model
- Plan mode tool uses conservative prompt for all users

Continues the USER_TYPE cleanup from #637 (dead code) and builds
on #639 (local feature flags).

* fix: address Copilot review comments — remove residual dead code

1. bridgeConfig.ts: ungate bridge override functions — return env vars
   directly instead of hardcoded undefined
2. bridgeMain.ts + initReplBridge.ts: ungate sessionIngressUrl — read
   CLAUDE_BRIDGE_SESSION_INGRESS_URL without USER_TYPE check
3. tools.ts: remove dead ConfigTool/TungstenTool imports, narrow
   eslint-disable scope, stub REPLTool/SuggestBackgroundPRTool to null
4. readOnlyValidation.ts: remove orphaned ANT_ONLY_COMMAND_ALLOWLIST
   and unused GH_READ_ONLY_COMMANDS import
5. insights.ts: remove entire remote collection plumbing (types,
   functions, options, display logic)
6. osc.ts: hardcode supportsTabStatus() to false (internal-only feature)
7. state.ts: simplify addSlowOperation/getSlowOperations to no-ops,
   remove dead constants

* fix: address Copilot review on PR #644

1. settings/types.ts: allow 'max' effort level for all users in Zod
   schema — was still gated behind USER_TYPE=ant, causing 'max' to be
   silently dropped on settings reload
2. shouldUseSandbox.ts: defensively normalize disabledCommands from
   feature flag config with Array.isArray() guards

* fix: address second round of Copilot review on PR #644

1. shouldUseSandbox.ts: validate top-level shape of disabledCommands
   before accessing properties (handles null/primitive from feature flag)
2. fullscreen.ts: update JSDoc to reflect removal of USER_TYPE default
3. osc.ts: update JSDoc — "Ant-only" → "Currently disabled"

src/bridge/bridgeConfig.ts

@@ -14,21 +14,14 @@
 import { getOauthConfig } from '../constants/oauth.js'
 import { getClaudeAIOAuthTokens } from '../utils/auth.js'
 
-/** Ant-only dev override: CLAUDE_BRIDGE_OAUTH_TOKEN, else undefined. */
+/** Dev override: CLAUDE_BRIDGE_OAUTH_TOKEN, else undefined. */
 export function getBridgeTokenOverride(): string | undefined {
-  return (
-    (process.env.USER_TYPE === 'ant' &&
-      process.env.CLAUDE_BRIDGE_OAUTH_TOKEN) ||
-    undefined
-  )
+  return process.env.CLAUDE_BRIDGE_OAUTH_TOKEN || undefined
 }
 
-/** Ant-only dev override: CLAUDE_BRIDGE_BASE_URL, else undefined. */
+/** Dev override: CLAUDE_BRIDGE_BASE_URL, else undefined. */
 export function getBridgeBaseUrlOverride(): string | undefined {
-  return (
-    (process.env.USER_TYPE === 'ant' && process.env.CLAUDE_BRIDGE_BASE_URL) ||
-    undefined
-  )
+  return process.env.CLAUDE_BRIDGE_BASE_URL || undefined
 }
 
 /**

src/bridge/bridgeMain.ts

@@ -2194,14 +2194,10 @@ export async function bridgeMain(args: string[]): Promise<void> {
 
   // Session ingress URL for WebSocket connections. In production this is the
   // same as baseUrl (Envoy routes /v1/session_ingress/* to session-ingress).
-  // Locally, session-ingress runs on a different port (9413) than the
-  // contain-provide-api (8211), so CLAUDE_BRIDGE_SESSION_INGRESS_URL must be
-  // set explicitly. Ant-only, matching CLAUDE_BRIDGE_BASE_URL.
+  // Locally, session-ingress may run on a different port, so
+  // CLAUDE_BRIDGE_SESSION_INGRESS_URL can override the default.
   const sessionIngressUrl =
-    process.env.USER_TYPE === 'ant' &&
-    process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL
-      ? process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL
-      : baseUrl
+    process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL || baseUrl
 
   const { getBranch, getRemoteUrl, findGitRoot } = await import(
     '../utils/git.js'
@@ -2851,10 +2847,7 @@ export async function runBridgeHeadless(
     )
   }
   const sessionIngressUrl =
-    process.env.USER_TYPE === 'ant' &&
-    process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL
-      ? process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL
-      : baseUrl
+    process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL || baseUrl
 
   const { getBranch, getRemoteUrl, findGitRoot } = await import(
     '../utils/git.js'

src/bridge/initReplBridge.ts

@@ -465,10 +465,7 @@ export async function initReplBridge(
   const branch = await getBranch()
   const gitRepoUrl = await getRemoteUrl()
   const sessionIngressUrl =
-    process.env.USER_TYPE === 'ant' &&
-    process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL
-      ? process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL
-      : baseUrl
+    process.env.CLAUDE_BRIDGE_SESSION_INGRESS_URL || baseUrl
 
   // Assistant-mode sessions advertise a distinct worker_type so the web UI
   // can filter them into a dedicated picker. KAIROS guard keeps the