Restructure tree by role; rename mizan-runtime → mizan-base

packages/ flattens into:
  backends/   server protocol adapters (mizan-django, mizan-ts)
  frontends/  client kernel + framework adapters (mizan-base, mizan-react, mizan-vue, mizan-svelte)
  workers/    runtime workers (mizan-ssr)
  cores/      shared language-level primitives (empty for now; mizan-python forthcoming)

The frontend kernel (was packages/mizan-runtime, now frontends/mizan-base) is
renamed to reflect its role — it's the shared base that frontend adapters
depend on directly. Reflects the substrate position that per-framework adapters
wrap a single shared kernel; codegen targets the adapter, not the raw kernel.

Path updates landed in: Makefile, two Gitea workflows, Dockerfile.test, four
example/harness config files, .claude/settings.local.json, four docs
(CLAUDE/ISSUES/ROADMAP/AFI_ARCHITECTURE), four codegen templates (stage1 +
react/vue/svelte adapters), and three package.jsons (the mizan-base rename
plus mizan-vue/svelte peerDeps).

Generated files under examples/django-react-site/harness/src/api/ still
reference @mizan/runtime — left as-is; they're regenerated artifacts and
the harness is non-functional pending the React wrapper-layer codegen.

Also folded in a pre-existing fix: the Gitea workflows had
working-directory: react / django pointing at a layout that predates
packages/, never updated.

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

backends/mizan-django/generate/generator/lib/fetch.mjs

@@ -0,0 +1,88 @@
+/**
+ * Schema Fetching
+ *
+ * Fetches mizan and channels schemas from Django management commands.
+ */
+
+import { spawn } from 'child_process'
+import path from 'path'
+
+/**
+ * Run a Django management command and parse JSON output.
+ */
+function runDjangoCommand(source, cwd, command) {
+  const managePath = path.resolve(cwd, source.django.managePath)
+  const manageDir = path.dirname(managePath)
+
+  let cmd, args
+  if (source.django.command) {
+    cmd = source.django.command[0]
+    args = [...source.django.command.slice(1), 'manage.py', command, '--indent', '0']
+  } else {
+    const python = source.django.python || 'python'
+    cmd = python
+    args = [managePath, command, '--indent', '0']
+  }
+
+  const env = source.django.env
+    ? { ...process.env, ...source.django.env }
+    : undefined
+
+  return new Promise((resolve, reject) => {
+    const proc = spawn(cmd, args, {
+      cwd: manageDir,
+      stdio: ['ignore', 'pipe', 'pipe'],
+      shell: process.platform === 'win32',
+      env,
+    })
+
+    let stdout = ''
+    let stderr = ''
+
+    proc.stdout.on('data', (data) => { stdout += data.toString() })
+    proc.stderr.on('data', (data) => { stderr += data.toString() })
+
+    proc.on('close', (code) => {
+      if (code !== 0) {
+        reject(new Error(`Django command failed (exit ${code}):\n${stderr}`))
+        return
+      }
+
+      const jsonStart = stdout.indexOf('{')
+      if (jsonStart === -1) {
+        reject(new Error(`No JSON found in Django output:\n${stdout}\n${stderr}`))
+        return
+      }
+
+      try {
+        resolve(JSON.parse(stdout.slice(jsonStart)))
+      } catch (err) {
+        reject(new Error(`Failed to parse JSON from Django:\n${err.message}\n${stdout}`))
+      }
+    })
+
+    proc.on('error', (err) => {
+      reject(new Error(`Failed to spawn Django command: ${err.message}`))
+    })
+  })
+}
+
+/**
+ * Fetch channels schema from Django.
+ */
+export async function fetchChannelsSchema(source, cwd) {
+  if (!source.django) {
+    throw new Error('Channels schema export requires django source configuration')
+  }
+  return runDjangoCommand(source, cwd, 'export_channels_schema')
+}
+
+/**
+ * Fetch mizan schema from Django.
+ */
+export async function fetchMizanSchema(source, cwd) {
+  if (!source.django) {
+    throw new Error('mizan schema export requires django source configuration')
+  }
+  return runDjangoCommand(source, cwd, 'export_mizan_schema')
+}