[codex] Add FlowRouter V0 POC hardware package

[FlowmemoryAI]

Summary

Adds the FlowRouter V0 proof-of-concept hardware package with docs, schemas, deterministic simulator output, fixtures, field-test plan, and a scope decision record.

Covers or advances:

• [hardware] Define FlowRouter v0 research scope and non-goals #11 FlowRouter v0 research scope and non-goals
• [hardware] Draft Meshtastic and LoRa control-message inventory #12 Meshtastic/LoRa control-message inventory
• [hardware] Draft FlowRouter enclosure concept v0 #30 FlowRouter enclosure concept v0
• [hardware] Prototype NFC memory cartridge v0 #31 NFC memory cartridge v0
• [hardware] Prototype FlowCore light-pipe status indicator #32 FlowCore light-pipe status indicator
• [hardware] Plan two-node FlowRouter Meshtastic demo #33 Two-node FlowRouter Meshtastic demo
• [hardware] Measure FlowRouter v0 CAD dimensions #34 CAD dimensions, advanced through measurement checklist and draft layout envelope; physical measurements still required
• [chain/appchain] Define appchain hardware node requirements #37 appchain hardware node requirements, advanced from the hardware observer/cache/diagnostic boundary only

What Changed

• Added hardware/README.md and organized FlowRouter, sidecar, memory cartridge, simulator, fixtures, and field-test structure.
• Added FlowRouter scope, BOM, assembly, printing, measurement, enclosure, and FlowCore light-pipe docs.
• Added Meshtastic/LoRa payload constraints, control-message inventory, and two-node field-test/demo plans.
• Added NFC Memory Cartridge metadata docs and future threat-model topics.
• Added JSON packet schemas and a deterministic Python simulator for device manifest, heartbeat, digest relays, compact receipt relay, cache status, gateway discovery, sidecar status, cartridge metadata, emergency/offline signal, and dashboard feed.
• Added generated sample fixture at hardware/fixtures/flowrouter_sample_seed42.json.
• Added decision record docs/DECISIONS/0001-flowrouter-v0-scope.md.
• Expanded hardware security assumptions in docs/SECURITY_MODEL.md.

Boundaries

• No ISP replacement claim.
• No broadband or heavy payloads over LoRa/Meshtastic.
• No custom RF board, antenna, amplifier, or production RF design.
• No production manufacturing or final CAD claim.
• No passive-income, mining, full-trustlessness, production L1, validator, or data-availability claim.

Validation

• python hardware/simulator/flowrouter_sim.py --seed 42 --out hardware/fixtures/flowrouter_sample_seed42.json
• python hardware/simulator/flowrouter_sim.py --validate-file hardware/fixtures/flowrouter_sample_seed42.json
• python -m py_compile hardware/simulator/flowrouter_sim.py
• deterministic fixture hash comparison from seed 42
• git diff --check
• whitespace / non-ASCII scan
• TODO/FIXME/placeholder scan
• allowed-scope check

Follow-Ups

• Fill [hardware] Measure FlowRouter v0 CAD dimensions #34 with actual hardware dimensions, cable clearances, thermal data, NFC read-through data, and power measurements.
• Have the appchain/chain agent own the non-hardware parts of [chain/appchain] Define appchain hardware node requirements #37.
• Decide a future device identity and packet authentication model before any state-changing sidecar commands.