Mizan-Rust backend adapter: server-side substrate + three-way parity

Adds first-class Rust-backed Mizan to sit alongside mizan-django and
mizan-fastapi. A Rust dev writes:

    #[derive(Mizan, Serialize, Deserialize)]
    pub struct ProfileOutput { pub user_id: i64, pub name: String }

    #[mizan::context("user")]
    pub struct UserCtx;

    #[mizan::client(context = UserCtx)]
    pub async fn user_profile(_req: &RequestHandle<'_>, user_id: i64) -> ProfileOutput { ... }

…and gets byte-identical KDL to the Python emitters, served over the
same wire protocol the React / Rust / Vue / Svelte kernels speak.

New crates:
- cores/mizan-rust/         (Cargo: mizan-core)     — IR types, KDL emitter, traits, registry,
                                                       runtime (compute_invalidation / compute_merges
                                                       ported from mizan-fastapi), graph_check with
                                                       structural type-matching
- cores/mizan-rust-macros/  (Cargo: mizan-macros)   — #[derive(Mizan)], #[mizan::context],
                                                       #[mizan::client] proc macros
- backends/mizan-rust-axum/ (Cargo: mizan-axum)     — axum HTTP adapter: /session/, /call/, /ctx/:name/
- tests/afi/rust_app/                                — AFI fixture port + server / export-ir binaries

Substrate-shape moves required by cross-language equivalence:
- IR canonicalization: functions / contexts / context-members / shared-by
  now sort alphabetically in both Python and Rust emitters. The IR is a
  contract; linkme doesn't preserve declaration order, so canonical sort
  is the only stable mapping. afi_ir.kdl + per-target baselines regenerated.
- MizanType::TYPE_NAME is a const (with a default type_name() reader) so
  it's usable in linkme TypeEntry static initializers.
- Tree-shaken type registry: #[derive(Mizan)] only emits the trait impl;
  the #[mizan::client] macro registers canonical-named entries from
  fn signatures, including Vec<T> element types for ref resolution.
- Merge resolution is structural (NamedType shape comparison) rather than
  by name — matches the Python types_match_for_merge semantics.

Three-way forcing functions:
- tests/afi/test_codegen_parity.py — Django ≡ FastAPI ≡ Rust on KDL bytes (3 pass)
- tests/rust/run_wire_parity.py    — 12/12 probes against FastAPI + Rust (EXIT=0)

Incidental fixes surfaced by the new tests:
- Stale `from .registry import validate_registry` import removed from
  mizan-django/setup/discovery.py (referenced a function that no longer
  exists; was masking codegen-parity).
- BASE_DIR added to tests/afi/django_app/project/settings.py.
- /session/ endpoint added to mizan-fastapi for protocol-shaped readiness
  probe parity (wire-parity harness now polls /api/mizan/session/ on both
  backends rather than FastAPI's /openapi.json).
- Root .gitignore picks up Rust target/ across the tree so new crates
  don't need per-crate gitignore.

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

protocol/mizan-codegen/tests/fixtures/baselines/vue/contexts/user.ts

@@ -2,11 +2,11 @@
 
 import { mizanFetch } from '@mizan/base'
 
-import type { userProfileOutput, userOrdersOutput } from '../types'
+import type { userOrdersOutput, userProfileOutput } from '../types'
 
 export interface UserContextData {
-    user_profile: userProfileOutput
     user_orders: userOrdersOutput
+    user_profile: userProfileOutput
 }
 
 export interface UserContextParams {

protocol/mizan-codegen/tests/fixtures/baselines/vue/index.ts

@@ -5,10 +5,10 @@ export * from './types'
 export { fetchUserContext, type UserContextData, type UserContextParams } from './contexts/user'
 
 export { callEcho } from './functions/echo'
-export { callWhoami } from './functions/whoami'
-export { callUpdateProfile } from './mutations/updateProfile'
 export { callFindUser } from './functions/findUser'
 export { callRenameUser } from './functions/renameUser'
+export { callUpdateProfile } from './mutations/updateProfile'
+export { callWhoami } from './functions/whoami'
 
 // Stage 2 framework adapter
 export * from './vue'

protocol/mizan-codegen/tests/fixtures/baselines/vue/vue.ts

@@ -3,7 +3,7 @@
 import { ref, computed, onMounted, onUnmounted, onServerPrefetch, type ComputedRef } from 'vue'
 import { registerContext, type ContextState } from '@mizan/base'
 
-import { fetchUserContext, type UserContextData, type UserContextParams, callUpdateProfile, callEcho, callWhoami, callFindUser, callRenameUser } from '../index'
+import { fetchUserContext, type UserContextData, type UserContextParams, callUpdateProfile, callEcho, callFindUser, callRenameUser, callWhoami } from '../index'
 
 export function useUserContext(params: UserContextParams) {
     const state = ref<ContextState<UserContextData>>({ data: null, status: 'idle', error: null })
@@ -25,8 +25,8 @@ export function useUserContext(params: UserContextParams) {
 
     return {
         state,
-        userProfile: computed(() => state.value.data?.user_profile ?? null) as ComputedRef<userProfileOutput | null>,
         userOrders: computed(() => state.value.data?.user_orders ?? null) as ComputedRef<userOrdersOutput | null>,
+        userProfile: computed(() => state.value.data?.user_profile ?? null) as ComputedRef<userProfileOutput | null>,
         loading: computed(() => state.value.status === 'loading'),
         error: computed(() => state.value.error),
     }
@@ -56,18 +56,6 @@ export function useEcho() {
     return { mutate, isPending, error }
 }
 
-export function useWhoami() {
-    const isPending = ref(false)
-    const error = ref<Error | null>(null)
-    async function mutate() {
-        isPending.value = true; error.value = null
-        try { return await callWhoami() }
-        catch (e) { error.value = e as Error; throw e }
-        finally { isPending.value = false }
-    }
-    return { mutate, isPending, error }
-}
-
 export function useFindUser() {
     const isPending = ref(false)
     const error = ref<Error | null>(null)
@@ -92,5 +80,17 @@ export function useRenameUser() {
     return { mutate, isPending, error }
 }
 
+export function useWhoami() {
+    const isPending = ref(false)
+    const error = ref<Error | null>(null)
+    async function mutate() {
+        isPending.value = true; error.value = null
+        try { return await callWhoami() }
+        catch (e) { error.value = e as Error; throw e }
+        finally { isPending.value = false }
+    }
+    return { mutate, isPending, error }
+}
+
 export type { ContextState } from '@mizan/base'
 export { configure, initSession, MizanError } from '@mizan/base'