chore: scaffold PYRE MVP monorepo (structure + docs)

pnpm + TypeScript workspace per design doc §13:
- apps/{web,api,worker} skeletons (Next.js 16, Fastify 5, BullMQ)
- packages/{core,solana,prometheus,db,config} (core has real types/DTOs;
  solana/prometheus are stubs)
- programs/pyre-core placeholder (future Anchor, v1.0)
- docs/: PYRE_MVP_DESIGN (canonical), ARCHITECTURE, SECURITY, TOKEN_CLASSIFICATION
- CLAUDE.md, README, .env.example (no private-key var by design)

Skeleton + docs only — no Solana/business logic yet. All workspaces typecheck clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pnpm-workspace.yaml

@@ -0,0 +1,19 @@
+packages:
+  - "apps/*"
+  - "packages/*"
+
+# Postinstall build-script approvals (pnpm). Only packages that ship prebuilt
+# binaries are allowed; the rest are optional native accelerations with pure-JS
+# fallbacks and are skipped to avoid needing a C/C++ toolchain on the server.
+allowBuilds:
+  esbuild: true          # prebuilt binary; used by tsx for dev
+  sharp: true            # prebuilt binary; Next.js image optimization
+  '@stellar/stellar-sdk': false
+  bigint-buffer: false
+  blake-hash: false
+  bufferutil: false
+  msgpackr-extract: false
+  protobufjs: false
+  tiny-secp256k1: false
+  usb: false             # ledger hardware-wallet native module; not needed for MVP
+  utf-8-validate: false