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>

workers/mizan-ssr/src/index.ts

@@ -0,0 +1,2 @@
+// The SSR package is a Bun worker subprocess (worker.tsx).
+// It is not imported as a library. Django's SSRBridge spawns it.

workers/mizan-ssr/src/test-worker.tsx

@@ -0,0 +1,29 @@
+/**
+ * Test SSR worker — registers simple components for the test suite.
+ */
+
+import { registerComponent } from './worker'
+
+// Simple component that renders props
+function Hello({ name }: { name: string }) {
+    return <div>Hello, {name}!</div>
+}
+
+// Component that renders a list
+function UserProfile({ user_id, name }: { user_id: number; name: string }) {
+    return (
+        <div className="profile">
+            <h1>{name}</h1>
+            <span>ID: {user_id}</span>
+        </div>
+    )
+}
+
+// Component that throws during render
+function Broken() {
+    throw new Error('Intentional render error')
+}
+
+registerComponent('Hello', Hello)
+registerComponent('UserProfile', UserProfile)
+registerComponent('Broken', Broken)

workers/mizan-ssr/src/worker.tsx

@@ -0,0 +1,72 @@
+import { renderToString } from 'react-dom/server'
+import { createElement } from 'react'
+
+const cache = new Map<string, any>()
+
+function respond(msg: Record<string, any>): void {
+    Bun.write(Bun.stdout, JSON.stringify(msg) + '\n')
+}
+
+async function handleMessage(msg: any): Promise<void> {
+    if (msg.method === 'ping') {
+        respond({ id: msg.id, pong: true })
+        return
+    }
+
+    if (msg.method === 'render') {
+        const { file, props } = msg.params ?? {}
+
+        if (!file) {
+            respond({ id: msg.id, error: 'Missing file path' })
+            return
+        }
+
+        try {
+            let mod = cache.get(file)
+            if (!mod) {
+                mod = await import(file)
+                cache.set(file, mod)
+            }
+
+            const Component = mod.default || Object.values(mod)[0]
+            if (!Component) {
+                respond({ id: msg.id, error: `No component exported from ${file}` })
+                return
+            }
+
+            const html = renderToString(createElement(Component, props ?? {}))
+            respond({ id: msg.id, html })
+        } catch (e: any) {
+            respond({ id: msg.id, error: e.message })
+        }
+        return
+    }
+
+    respond({ id: msg.id, error: `Unknown method: ${msg.method}` })
+}
+
+async function processInput(): Promise<void> {
+    const reader = Bun.stdin.stream().getReader()
+    const decoder = new TextDecoder()
+    let buffer = ''
+
+    while (true) {
+        const { done, value } = await reader.read()
+        if (done) break
+
+        buffer += decoder.decode(value, { stream: true })
+
+        let i: number
+        while ((i = buffer.indexOf('\n')) !== -1) {
+            const line = buffer.slice(0, i).trim()
+            buffer = buffer.slice(i + 1)
+            if (line) {
+                try { await handleMessage(JSON.parse(line)) }
+                catch (e: any) { respond({ id: -1, error: e.message }) }
+            }
+        }
+    }
+}
+
+respond({ id: 0, ready: true })
+processInput()