docs: add Sepolia ↔ Miden bridging tutorial via Epoch (+ examples/bridging-app)

[Keinberger]

Summary

This PR ships a single-page web-client tutorial (docs/src/web-client/bridging_with_epoch_tutorial.md) covering Miden↔Sepolia bridging via the Epoch protocol intent SDK, plus a runnable Vite + React reference app under examples/bridging-app/ that the tutorial's snippets paste-verify against.

The tutorial is framed as a guided tour of the reference app: clone it, run it, then read the steps as annotations on the integration points you'd port into your own Miden frontend. Every fenced code block is byte-identical to a slice of examples/bridging-app/src/..., with a preceding **From <file> (lines X–Y):** prose line plus an HTML <!-- source: ... --> comment that the agent task-workflow verifier checks against the real source. Both directions were exercised live on Sepolia + Miden testnet through a wallet-enabled Playwright MCP browser — forward: EVM tx 0xe8d4eb1b…1112 status: success with P2IDE note 0xc03ec01…cc798 consumed on Miden; reverse: Sepolia compact-deposit tx 0xe0e7f415…a063ad86 with Miden P2ID note 0x5d577237…612c5378 delivered to the recipient wallet.

Companion sidebar + Bridging DocCard in 0xMiden/docs#297.

Key Changes

• Tutorial with four steps — SDK wiring, Miden → EVM bridge, EVM → Miden bridge, and how the Miden Wallet consumes the delivered P2ID note — plus eleven inherited Epoch pitfalls and an eleven-method EpochIntentSDK API reference card sourced to dist/index.d.ts line ranges.
• examples/bridging-app/ forked from epochprotocol/miden-integration-example@efc3a690 with bridging-specific adaptations: midenReclaimHeight computed at the call site as currentMidenBlock + 1000 (was a literal upstream), env-driven VITE_RAINBOWKIT_PROJECT_ID + VITE_ALLOCATOR_URL, auto-derived Miden faucet ID for known tokens, shared MidenWalletAdapterProvider context so the wallet's requestAssets() popup fires once per page load instead of per consumer, lazy-mount-then-keep tabs so an in-flight withdraw quote survives a tab switch, and an informational WithdrawConsume panel that points readers at the auto-consumed P2ID note on Midenscan.
• Bigint-safe Miden balance formatting in the Source-asset dropdown and Balance: label — uses viem's formatUnits against the faucet's decimals instead of Number(amount) (the raw base-unit display was a real bug surfaced live by a fresh-reader pass through the tutorial).
• Browser title Miden x Epoch Bridge replacing the scaffold default.
• 38 Vitest tests across the formatter helper, the WithdrawConsume panel, and the IntentForm balance render; tsc -b --noEmit, vite build, prettier --check "**/*.md", yarn lint, the docs npm run build:dev, and the snippet verifier all clean.

Out of scope

• No Agglayer tutorial — the tutorial's "When to use Epoch vs Agglayer" disclaimer points at protocol/crates/miden-agglayer/SPEC.md. A web-Agglayer tutorial will be its own PR after a feasibility pass.

Open Questions

1. Tutorial word count: the tutorial sits at 2,500 words exactly (the documented band ceiling). Happy to trim a couple of pitfalls or fold the API reference card into a collapsed <details> if you'd prefer breathing room.
2. DocCard placement: the companion docs PR puts Bridging as the 4th card in the tutorials index. Happy to move it earlier in the order or rename it if Brian wants a different IA.

Reviewers: Brian (docs IA), an Epoch team rep for technical accuracy, Keinberger for voice.

[BrianSeong99]

Did a fresh pass against the latest PR head and the current Epoch materials, some feedbacks!

1 Status polling should be destination-chain aware.

The latest Epoch example does not treat “first non-Miden status row” as the final EVM settlement. It filters status rows to the actual destination chain, waits while any destination-chain row is still pending, then takes the last destination-chain success.

This PR currently does:

• useIntentFlowStatus.ts: statuses.find((s) => Number(s.chainId) !== MIDEN_CHAIN_ID)
• IntentForm.tsx: evmStatuses.find(...)

That can pick up an internal Compact/SIO row instead of the user’s destination-chain settlement. The upstream example explicitly calls this out because SIO can surface a prior-step success alongside an in-flight destination-chain tx.

Can we port the destination-chain-aware logic from the latest Epoch example into this PR? Just to make sure dvelopers/agents are aware of potential unsettled transctions in the list.

2 The midenConsumed wording doesn’t match the app code.

The Epoch GitBook’s raw /miden/status/... example mentions midenConsumed, but this app uses sdk.getIntentStatus(...), which returns IntentTransactionStatus[]. The local IntentFlowStatus type has evmCompleted, midenTxId, midenStatus, and midenNoteId, but no midenConsumed.

So this sentence should either be rewritten to match the SDK-row flow, or the app should actually call/type the raw /miden/status endpoint if midenConsumed is the intended success signal.

3 Please remove internal Epoch implementation names from public comments.

There are a few public source comments that mention internal service names / source paths, e.g. dex-solver inventory, epoch-sio/src/.... Since this is a public Miden tutorial, I’d keep the wording at the protocol/API level: “allocator”, “Epoch status API”, “Miden virtual chain id”, etc.