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/format-shared.ts

@@ -0,0 +1,49 @@
+import color from "picocolors"
+import type { CheckStatus, DoctorIssue } from "./types"
+import { SYMBOLS, STATUS_COLORS } from "./constants"
+
+export function formatStatusSymbol(status: CheckStatus): string {
+  const colorFn = STATUS_COLORS[status]
+  switch (status) {
+    case "pass":
+      return colorFn(SYMBOLS.check)
+    case "fail":
+      return colorFn(SYMBOLS.cross)
+    case "warn":
+      return colorFn(SYMBOLS.warn)
+    case "skip":
+      return colorFn(SYMBOLS.skip)
+  }
+}
+
+export function formatStatusMark(available: boolean): string {
+  return available ? color.green(SYMBOLS.check) : color.red(SYMBOLS.cross)
+}
+
+export function stripAnsi(str: string): string {
+  const ESC = String.fromCharCode(27)
+  const pattern = ESC + "\\[[0-9;]*m"
+  return str.replace(new RegExp(pattern, "g"), "")
+}
+
+export function formatHeader(): string {
+  return `\n${color.bgMagenta(color.white(" oMo Doctor "))}\n`
+}
+
+export function formatIssue(issue: DoctorIssue, index: number): string {
+  const lines: string[] = []
+  const severityColor = issue.severity === "error" ? color.red : color.yellow
+
+  lines.push(`${index}. ${severityColor(issue.title)}`)
+  lines.push(`   ${color.dim(issue.description)}`)
+
+  if (issue.fix) {
+    lines.push(`   ${color.cyan("Fix:")} ${color.dim(issue.fix)}`)
+  }
+
+  if (issue.affects && issue.affects.length > 0) {
+    lines.push(`   ${color.cyan("Affects:")} ${color.dim(issue.affects.join(", "))}`)
+  }
+
+  return lines.join("\n")
+}