Restore documentation layer — match current substrate

ROADMAP: done items moved out of "Next" (codegen rewrite, SSR bridge,
edge manifest, X-Mizan-Invalidate, return-type branching, affects_params,
kernel extraction, two-stage codegen, mizan-ts). Real "Next" in:
framework-adapter wrapper layer (MizanContext + useMizan + DjangoError
on top of the kernel) for React/Vue/Svelte; A1–A4 from ISSUES.md.

CLAUDE: 4-package layout replaced with the actual 7-package layered
architecture (backend protocol adapters + frontend kernel + framework
adapters + SSR worker). "STALE codegen" section rewritten to describe
what's emitted vs. the wrapper layer that isn't yet.

docs/ now tracked (6 files). AFI_ARCHITECTURE rewritten — replaced
the speculative `mizan-ast`/`mizan-csr`/`mizan-rpc`/`mizan-schema`
package names with the real layout, dropped KDL-schema language for
the actual schema-export format. The other 5 docs/ files were already
current and are tracked as-is.

ARCHITECTURE-REWORK.md deleted — same expert review is re-tracked in
the fresher ISSUES.md, two parallel trackers was sediment.

README.md deleted — drift was beyond surgical fixes (`mizan_clients.py`
convention, `<DjangoContext>` provider, removed `@compose` and
`context='local'`, wrong codegen output filenames, 3-package structure
vs. 7). Rewrite waits for the wrapper-layer codegen to land so
user-facing examples reflect reality.

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

docs/PRODUCT_ARCHITECTURE.md

@@ -0,0 +1,61 @@
+# Product Architecture
+
+*Revised April 2026.*
+
+## Launch product: Mizan Render
+
+**$20/seat/month.**
+
+Protocol-aware Edge caching + PSR delivery via Cloudflare + render
+Workers + TS backend hosting via Workers for Platforms.
+
+Developer's stack = their backend + database. Cloudflare handles
+read traffic, rendering, and caching.
+
+## Deferred: Mizan Deploy
+
+Django hosting requires IaaS compliance: gVisor, KMS, NIS2,
+multi-state privacy. ~$5–8K legal costs.
+
+**Deferred until Render revenue funds it.**
+
+TS "Deploy" exists via Workers for Platforms at no additional
+compliance cost.
+
+## Free framework: mizan-cache (origin-side cache)
+
+Python package implementing the **full cache protocol locally** —
+same HMAC key derivation, metadata schema, and purge semantics as
+Edge.
+
+Three backends:
+
+- In-memory dict (default)
+- Redis
+- SQLite
+
+### Dual purpose
+
+1. Makes the free framework genuinely powerful (PSR + typed hooks +
+   invalidation + caching with zero cost).
+2. Provides a unit-testable surface for all cache mechanics without
+   Cloudflare.
+
+## Spec additions
+
+- `@client(cache=False)` — uncacheable; emits `Cache-Control: no-store`.
+- Cache ABI: `get(key)`, `put(key, response, metadata)`,
+  `purge(context, params)`.
+
+## Launch compliance (Render only)
+
+Entirely Cloudflare Workers + management API (Django/Postgres):
+
+- GDPR DPA + privacy policy + subprocessor list — ~$500–1K legal
+- DMCA — $6
+- No NIS2, no gVisor, no KMS
+
+## Invariant
+
+All architecture decisions target the Render-only launch posture.
+Don't build Deploy infrastructure prematurely.