[release] FlowChain private testnet setup package

[FlowmemoryAI]

Summary

This release branch integrates the FlowChain private/local testnet PR stack (#83-#90) into one setup branch and adds the missing guarded Base bridge POC lane.

It adds:

• one-command Windows setup via START_FLOWCHAIN_LOCAL.ps1
• beginner guide in docs/EASY_SECOND_COMPUTER_SETUP.md
• integrated local devnet/control-plane/workbench/crypto/hardware fixtures
• bridge POC contract, Foundry tests, schemas, fixture, relayer package, and Base Sepolia/mainnet-canary guardrail scripts

Second-computer command

git clone -b release/flowchain-private-testnet https://github.com/FlowmemoryAI/FlowMemory.git
cd FlowMemory
powershell -ExecutionPolicy Bypass -File .\START_FLOWCHAIN_LOCAL.ps1

Checks run

• npm run launch:candidate
• npm test
• cargo test --manifest-path crates/flowmemory-devnet/Cargo.toml
• npm run build --prefix apps/dashboard
• npm test --prefix crypto
• forge test --match-path tests/bridge/BaseBridgeLockbox.t.sol
• npm run bridge:test
• npm run bridge:mock
• powershell -NoProfile -ExecutionPolicy Bypass -File .\START_FLOWCHAIN_LOCAL.ps1 -SkipInstall -NoServers
• git diff --check
• node infra/scripts/check-unsafe-claims.mjs

Boundaries

This is a local/private testnet package and bridge POC only. It is not production mainnet, not public validator software, not tokenomics, not audited cryptography, and not a production bridge.