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/index.mjs

@@ -0,0 +1,164 @@
+/**
+ * Index File Generator
+ *
+ * Generates a consolidated index.ts that re-exports everything
+ * from the generated files for clean imports.
+ */
+
+function pascalCase(str) {
+  return str.charAt(0).toUpperCase() + str.slice(1)
+}
+
+function toPascalCase(str) {
+  return str
+    .split(/[.\-_]/)
+    .map(part => part.charAt(0).toUpperCase() + part.slice(1))
+    .join('')
+}
+
+/**
+ * Generate the consolidated index.ts file.
+ */
+export function generateIndex({ channelsSchema, mizanSchema }) {
+  const lines = [
+    '/**',
+    ' * mizan API - Consolidated Exports',
+    ' *',
+    ' * Import everything from here:',
+    ' *',
+    ' * @example',
+    ' * ```tsx',
+    ' * import {',
+    ' *     MizanContext,',
+    ' *     useCurrentUser,',
+    ' *     useEcho,',
+    ' *     useChatChannel,',
+    ' * } from \'@/api\'',
+    ' * ```',
+    ' */',
+    '',
+    '// AUTO-GENERATED by mizan - do not edit manually',
+    '// Regenerate with: npm run schemas',
+    '',
+  ]
+
+  const functions = mizanSchema?.['x-mizan-functions'] || []
+  const contextGroups = mizanSchema?.['x-mizan-contexts'] || {}
+  const hasMizan = functions.length > 0
+
+  if (hasMizan) {
+    const globalContexts = functions.filter(fn => fn.isContext === 'global')
+    const regularFunctions = functions.filter(fn => !fn.isContext && !fn.isForm)
+    const namedContextEntries = Object.entries(contextGroups).filter(([name]) => name !== 'global')
+
+    lines.push('// =============================================================================')
+    lines.push('// mizan Provider & Hooks')
+    lines.push('// =============================================================================')
+    lines.push('')
+
+    // Server exports
+    if (globalContexts.length > 0) {
+      lines.push('export {')
+      lines.push('    getMizanHydration,')
+      lines.push('    getDjangoHydration,')
+      lines.push('    type MizanHydrationData,')
+      lines.push('    type DjangoHydration,')
+      lines.push("} from './generated.server'")
+      lines.push('')
+    }
+
+    // Client exports
+    lines.push('export {')
+    lines.push('    // Provider')
+    lines.push('    MizanContext,')
+    lines.push('    type MizanContextProps,')
+    lines.push('    DjangoContext,')
+    lines.push('    type DjangoContextProps,')
+
+    // Global context hooks
+    if (globalContexts.length > 0) {
+      lines.push('')
+      lines.push('    // Global context hooks')
+      for (const ctx of globalContexts) {
+        const hookPascal = pascalCase(ctx.camelName)
+        lines.push(`    use${hookPascal},`)
+      }
+      lines.push('')
+      lines.push('    // Refresh hooks')
+      lines.push('    useMizanRefresh,')
+      lines.push('    useDjangoRefresh,')
+    }
+
+    // Named context providers and hooks
+    if (namedContextEntries.length > 0) {
+      lines.push('')
+      lines.push('    // Named context providers')
+      for (const [ctxName, ctxMeta] of namedContextEntries) {
+        const ctxPascal = toPascalCase(ctxName)
+        lines.push(`    ${ctxPascal}Context,`)
+        // Hooks for this context's functions
+        const ctxFunctions = functions.filter(fn => fn.isContext === ctxName)
+        for (const fn of ctxFunctions) {
+          const hookPascal = pascalCase(fn.camelName)
+          lines.push(`    use${hookPascal},`)
+        }
+      }
+    }
+
+    // Function hooks (mutations + plain)
+    if (regularFunctions.length > 0) {
+      lines.push('')
+      lines.push('    // Function hooks')
+      for (const fn of regularFunctions) {
+        const pascal = pascalCase(fn.camelName)
+        lines.push(`    use${pascal},`)
+      }
+    }
+
+    lines.push('')
+    lines.push('    // Re-exports from mizan library')
+    lines.push('    useMizan,')
+    lines.push('    useMizanStatus,')
+    lines.push('    usePush,')
+    lines.push('    DjangoError,')
+    lines.push('    type ConnectionStatus,')
+    lines.push('    type PushMessage,')
+    lines.push('    type PushListener,')
+    lines.push("} from './generated.provider'")
+    lines.push('')
+  }
+
+  // ==========================================================================
+  // Channel Hooks
+  // ==========================================================================
+
+  const channels = channelsSchema?.['x-mizan-channels'] || []
+
+  if (channels.length > 0) {
+    lines.push('// =============================================================================')
+    lines.push('// Channel Hooks')
+    lines.push('// =============================================================================')
+    lines.push('')
+    lines.push('export {')
+    for (const ch of channels) {
+      lines.push(`    use${ch.pascalName}Channel,`)
+    }
+    lines.push("} from './generated.channels.hooks'")
+    lines.push('')
+
+    lines.push('// =============================================================================')
+    lines.push('// Channel Types')
+    lines.push('// =============================================================================')
+    lines.push('')
+    lines.push('export type {')
+    for (const ch of channels) {
+      if (ch.hasParams) lines.push(`    ${ch.paramsType},`)
+      if (ch.hasReactMessage) lines.push(`    ${ch.reactMessageType},`)
+      if (ch.hasDjangoMessage) lines.push(`    ${ch.djangoMessageType},`)
+    }
+    lines.push("} from './generated.channels'")
+    lines.push('')
+  }
+
+  return lines.join('\n')
+}