Move codegen out of mizan-django: protocol/mizan-generate/

The codegen consumes a schema from any backend and emits typed client
code for any frontend — it doesn't belong inside a backend adapter.
That placement was historical sediment from when there was only a
Django backend; it predates the AFI generalization.

New top-level slot: `protocol/` for protocol-level tooling. Tree is
now:

  backends/    server protocol adapters
  frontends/   client kernel + per-framework adapters
  cores/       shared language-level primitives
  protocol/    protocol-level tooling
  workers/     runtime workers / bridges

Codegen moves to `protocol/mizan-generate/`. Same file layout under
`generator/` (cli.mjs, lib/), preserved via git mv.

Package metadata cleaned up:
- name: "generate" (placeholder) → "mizan-generate"
- description filled in
- type: module (cli.mjs is .mjs ESM, was previously declared "commonjs")
- bin entry added so `npx mizan-generate --config <config.mjs>` works
  once the package is published, instead of `node path/to/cli.mjs`.

Path-reference fixups:
- backends/mizan-django/README.md: `node path/to/...` → `npx mizan-generate`
- backends/mizan-fastapi/README.md: same
- ISSUES.md: file paths in three issue entries
- CLAUDE.md: codegen description + Package Layout section refreshed
  (added protocol/, mizan-fastapi entry, mizan-python entry)
- docs/AFI_ARCHITECTURE.md: Package Layout refreshed identically

Verified codegen runs from new location: regenerated the FastAPI
example harness's api/ output, identical to pre-move.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

protocol/mizan-generate/generator/lib/adapters/vue.mjs

@@ -0,0 +1,104 @@
+/**
+ * Vue Stage 2 — Generates composables from Stage 1 output.
+ *
+ * Subscribes to the kernel for state. Vue reactivity wraps kernel notifications.
+ */
+
+function pascalCase(str) {
+    return str.split(/[.\-_]/).map(p => p.charAt(0).toUpperCase() + p.slice(1)).join('')
+}
+
+export function generateVueAdapter(schema) {
+    const functions = schema['x-mizan-functions'] || []
+    const contextGroups = schema['x-mizan-contexts'] || {}
+    const mutations = functions.filter(fn => !fn.isContext && !fn.isForm && fn.affects)
+    const plainFns = functions.filter(fn => !fn.isContext && !fn.isForm && !fn.affects)
+
+    const lines = [
+        '// AUTO-GENERATED by mizan — do not edit',
+        '',
+        "import { ref, computed, onMounted, onUnmounted, onServerPrefetch, type ComputedRef } from 'vue'",
+        "import { registerContext, type ContextState } from '@mizan/base'",
+        '',
+    ]
+
+    const stage1Imports = []
+    for (const [ctxName] of Object.entries(contextGroups)) {
+        const p = pascalCase(ctxName)
+        stage1Imports.push(`fetch${p}Context`, `type ${p}ContextData`, `type ${p}ContextParams`)
+    }
+    for (const fn of [...mutations, ...plainFns]) {
+        stage1Imports.push(`call${pascalCase(fn.camelName)}`)
+    }
+    if (stage1Imports.length > 0) {
+        lines.push(`import { ${stage1Imports.join(', ')} } from '../index'`)
+        lines.push('')
+    }
+
+    for (const [ctxName, ctxMeta] of Object.entries(contextGroups)) {
+        const p = pascalCase(ctxName)
+        const ctxFunctions = functions.filter(fn => fn.isContext === ctxName)
+        const paramEntries = Object.entries(ctxMeta.params || {})
+        const paramsArg = paramEntries.length > 0 ? 'params' : '{} as any'
+
+        if (paramEntries.length > 0) {
+            lines.push(`export function use${p}Context(params: ${p}ContextParams) {`)
+        } else {
+            lines.push(`export function use${p}Context() {`)
+        }
+
+        lines.push(`    const state = ref<ContextState<${p}ContextData>>({ data: null, status: 'idle', error: null })`)
+        lines.push(`    let handle: ReturnType<typeof registerContext> | null = null`)
+        lines.push('')
+        lines.push(`    onMounted(() => {`)
+        lines.push(`        handle = registerContext('${ctxName}', ${paramsArg}, () => fetch${p}Context(${paramsArg}))`)
+        lines.push(`        handle.subscribe(() => { state.value = handle!.getState() })`)
+        lines.push(`        handle.refetch()`)
+        lines.push(`    })`)
+        lines.push('')
+        lines.push(`    onServerPrefetch(async () => {`)
+        lines.push(`        handle = registerContext('${ctxName}', ${paramsArg}, () => fetch${p}Context(${paramsArg}))`)
+        lines.push(`        await handle.refetch()`)
+        lines.push(`        state.value = handle.getState()`)
+        lines.push(`    })`)
+        lines.push('')
+        lines.push(`    onUnmounted(() => { handle?.unregister() })`)
+        lines.push('')
+        lines.push(`    return {`)
+        lines.push(`        state,`)
+        for (const fn of ctxFunctions) {
+            lines.push(`        ${fn.camelName}: computed(() => state.value.data?.${fn.name} ?? null) as ComputedRef<${fn.outputType} | null>,`)
+        }
+        lines.push(`        loading: computed(() => state.value.status === 'loading'),`)
+        lines.push(`        error: computed(() => state.value.error),`)
+        lines.push(`    }`)
+        lines.push('}')
+        lines.push('')
+    }
+
+    for (const fn of [...mutations, ...plainFns]) {
+        const p = pascalCase(fn.camelName)
+        lines.push(`export function use${p}() {`)
+        lines.push(`    const isPending = ref(false)`)
+        lines.push(`    const error = ref<Error | null>(null)`)
+        if (fn.hasInput) {
+            lines.push(`    async function mutate(args: Parameters<typeof call${p}>[0]) {`)
+        } else {
+            lines.push(`    async function mutate() {`)
+        }
+        lines.push(`        isPending.value = true; error.value = null`)
+        lines.push(`        try { return await call${p}(${fn.hasInput ? 'args' : ''}) }`)
+        lines.push(`        catch (e) { error.value = e as Error; throw e }`)
+        lines.push(`        finally { isPending.value = false }`)
+        lines.push(`    }`)
+        lines.push(`    return { mutate, isPending, error }`)
+        lines.push('}')
+        lines.push('')
+    }
+
+    lines.push("export type { ContextState } from '@mizan/base'")
+    lines.push("export { configure, initSession, MizanError } from '@mizan/base'")
+    lines.push('')
+
+    return lines.join('\n')
+}