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/PSR_VS_EDGE.md

@@ -0,0 +1,38 @@
+# PSR vs Edge Delivery
+
+Two distinct layers that prior conversations have conflated. They are
+independent.
+
+## PSR — Preemptive Static Rendering
+
+**Protocol feature.** Render HTML on mutation, not on request.
+
+Mechanism: `@client` fires mutation → backend adapter triggers local
+render runtime → HTML stored locally.
+
+Works on a $5 VPS with local Bun. **No Edge required.** PSR is part
+of the protocol; it's available to every Mizan deployment regardless
+of hosting.
+
+## Edge Delivery — Mizan Render (Paid Product)
+
+Pre-rendered HTML cached globally on Cloudflare CDN.
+
+Uses `fetch()` to a render Worker on a separate domain
+(`render.mizan.cloud`) instead of `cache.put()`, because Workers
+Cache API is per-datacenter only. `fetch()` across zones goes through
+the global CDN cache path with Tiered Cache.
+
+This layer is the paid Mizan Render product.
+
+## Caching modes
+
+- **Public content** — preemptive (render on mutation)
+- **User-scoped content** — reactive only (purge on mutation, render
+  on next request)
+
+## Invariant
+
+PSR logic must not couple to Cloudflare-specific APIs. PSR must work
+without any cloud infrastructure. Edge delivery extends PSR; it does
+not replace it.