chore: dev environment — signet testnet stack, mock LND RPCs, faucet button

Switch docker-compose from regtest to signet, add standalone testnet stack
(docker-compose.testnet.yml) with Bitcoin+LND+ThunderHub+Fedimint. Mock
backend now auto-detects Podman/Docker sockets and includes full LND/Lightning
RPC mocks. Dev scripts refactored with boot mode, testnet option, and macOS
EAGAIN fix for port cleanup. Added dev faucet button to Home.vue.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

testnet/README.md

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+# Lightning Testnet Stack (Signet)
+
+Real Bitcoin signet + LND + ThunderHub + Fedimint for testing Lightning features.
+
+## Quick Start
+
+```bash
+docker compose -f docker-compose.testnet.yml up -d
+```
+
+First run takes ~10 minutes for signet blockchain sync (~200MB).
+
+## Access
+
+| Service | URL | Credentials |
+|---------|-----|-------------|
+| ThunderHub | http://localhost:3010 | password: `thunderhub` |
+| Fedimint Guardian UI | http://localhost:18175 | — |
+| LND REST API | http://localhost:8080 | — |
+| Bitcoin RPC | localhost:38332 | user: `bitcoin` / pass: `bitcoinpass` |
+
+## Get Signet Coins
+
+1. Get a new address: `docker exec archy-lnd-signet lncli --network=signet newaddress p2wkh`
+2. Visit https://signetfaucet.com and paste the address
+3. Wait for 1 confirmation (~10 min)
+4. Check balance: `docker exec archy-lnd-signet lncli --network=signet walletbalance`
+
+## Open a Lightning Channel
+
+```bash
+# Connect to a signet peer (example: ACINQ signet node)
+docker exec archy-lnd-signet lncli --network=signet connect 03...@signet-node:9735
+
+# Open channel (amount in sats)
+docker exec archy-lnd-signet lncli --network=signet openchannel --node_key=03... --local_amt=100000
+```
+
+Or use ThunderHub's UI at http://localhost:3010 to manage channels visually.
+
+## Create & Pay Invoices
+
+```bash
+# Create invoice
+docker exec archy-lnd-signet lncli --network=signet addinvoice --amt=1000 --memo="test payment"
+
+# Pay invoice (from another node or ThunderHub)
+docker exec archy-lnd-signet lncli --network=signet payinvoice <bolt11>
+```
+
+## Useful Commands
+
+```bash
+# Node info
+docker exec archy-lnd-signet lncli --network=signet getinfo
+
+# List channels
+docker exec archy-lnd-signet lncli --network=signet listchannels
+
+# Check Bitcoin sync progress
+docker exec archy-bitcoind-signet bitcoin-cli -signet -rpcuser=bitcoin -rpcpassword=bitcoinpass -rpcport=38332 getblockchaininfo
+
+# View logs
+docker compose -f docker-compose.testnet.yml logs -f lnd-signet
+docker compose -f docker-compose.testnet.yml logs -f thunderhub-signet
+
+# Stop everything
+docker compose -f docker-compose.testnet.yml down
+
+# Reset all data (fresh start)
+docker compose -f docker-compose.testnet.yml down -v
+```
+
+## Architecture
+
+```
+bitcoind-signet (port 38332)
+    ↓ RPC + ZMQ
+lnd-signet (gRPC 10009, REST 8080, P2P 9735)
+    ↓ macaroon + TLS
+thunderhub-signet (web UI on 3010)
+
+bitcoind-signet
+    ↓ RPC
+fedimint-signet (Guardian UI on 18175, API on 18174)
+```
+
+All containers share the `signet-net` bridge network for internal DNS resolution.

testnet/thunderhub-config.yaml

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+# ThunderHub account config — connects to LND signet node
+# The LND data volume is mounted read-only at /lnd-data
+masterPassword: "thunderhub"
+accounts:
+  - name: "Archy Signet"
+    serverUrl: "lnd-signet:10009"
+    macaroonPath: "/lnd-data/data/chain/bitcoin/signet/admin.macaroon"
+    certificatePath: "/lnd-data/tls.cert"