refactor(doctor): redesign with 3-tier output and consolidated checks

Consolidate 16 separate checks into 5 (system, config, providers, tools, models).
Add 3-tier formatting: default (problems-only), --status (dashboard), --verbose (deep diagnostics).
Read actual loaded plugin version from opencode cache directory.
Check environment variables for provider authentication.

src/cli/doctor/checks/system-plugin.ts

@@ -0,0 +1,95 @@
+import { existsSync, readFileSync } from "node:fs"
+
+import { PACKAGE_NAME } from "../constants"
+import { getOpenCodeConfigPaths, parseJsonc } from "../../../shared"
+
+export interface PluginInfo {
+  registered: boolean
+  configPath: string | null
+  entry: string | null
+  isPinned: boolean
+  pinnedVersion: string | null
+  isLocalDev: boolean
+}
+
+interface OpenCodeConfigShape {
+  plugin?: string[]
+}
+
+function detectConfigPath(): string | null {
+  const paths = getOpenCodeConfigPaths({ binary: "opencode", version: null })
+  if (existsSync(paths.configJsonc)) return paths.configJsonc
+  if (existsSync(paths.configJson)) return paths.configJson
+  return null
+}
+
+function parsePluginVersion(entry: string): string | null {
+  if (!entry.startsWith(`${PACKAGE_NAME}@`)) return null
+  const value = entry.slice(PACKAGE_NAME.length + 1)
+  if (!value || value === "latest") return null
+  return value
+}
+
+function findPluginEntry(entries: string[]): { entry: string; isLocalDev: boolean } | null {
+  for (const entry of entries) {
+    if (entry === PACKAGE_NAME || entry.startsWith(`${PACKAGE_NAME}@`)) {
+      return { entry, isLocalDev: false }
+    }
+    if (entry.startsWith("file://") && entry.includes(PACKAGE_NAME)) {
+      return { entry, isLocalDev: true }
+    }
+  }
+
+  return null
+}
+
+export function getPluginInfo(): PluginInfo {
+  const configPath = detectConfigPath()
+  if (!configPath) {
+    return {
+      registered: false,
+      configPath: null,
+      entry: null,
+      isPinned: false,
+      pinnedVersion: null,
+      isLocalDev: false,
+    }
+  }
+
+  try {
+    const content = readFileSync(configPath, "utf-8")
+    const parsedConfig = parseJsonc<OpenCodeConfigShape>(content)
+    const pluginEntry = findPluginEntry(parsedConfig.plugin ?? [])
+    if (!pluginEntry) {
+      return {
+        registered: false,
+        configPath,
+        entry: null,
+        isPinned: false,
+        pinnedVersion: null,
+        isLocalDev: false,
+      }
+    }
+
+    const pinnedVersion = parsePluginVersion(pluginEntry.entry)
+    return {
+      registered: true,
+      configPath,
+      entry: pluginEntry.entry,
+      isPinned: pinnedVersion !== null,
+      pinnedVersion,
+      isLocalDev: pluginEntry.isLocalDev,
+    }
+  } catch {
+    return {
+      registered: false,
+      configPath,
+      entry: null,
+      isPinned: false,
+      pinnedVersion: null,
+      isLocalDev: false,
+    }
+  }
+}
+
+export { detectConfigPath, findPluginEntry }