Add bounty + contract documentation after chain v0.4.0 lands

[proofmancer]

Tracking issue for the docs.ligate.io work that follows chain v0.4.0 (bounty + contract modules). Adds reference pages, command pages, SDK pages, plus two worked-example walkthroughs that compose chain + CLI + SDK end-to-end.

Dependencies

• Blocked on chain v0.4.0 shipping (so the docs can quote real contract addresses + working CLI invocations).
• Soft dependency on ligate-api + ligate-cli + ligate-js sub-tasks landing (so doc examples can reference real endpoints / commands / SDK methods).

Scope

REST API reference (new pages)

• /api/bounties/get-matching — GET /v1/bounties/matching/{address} (already partially live; docs need expanding)
• /api/bounties/get-by-id — GET /v1/bounties/{bountyId}
• /api/bounties/get-by-poster — GET /v1/addresses/{address}/bounties
• /api/contracts/get-matching — GET /v1/contracts/matching/{address}
• /api/contracts/get-by-id — GET /v1/contracts/{contractId}
• /api/contracts/get-by-poster — GET /v1/addresses/{address}/contracts
• /api/events/bounty — payload schemas for the 5 bounty event variants
• /api/events/contract — payload schemas for the 8 contract event variants

CLI reference (new pages)

• /cli/bounty/post, /cli/bounty/claim, /cli/bounty/dispute, /cli/bounty/resolve, /cli/bounty/cancel
• /cli/bounty/list-matching, /cli/bounty/show
• /cli/contract/post, /cli/contract/commit, /cli/contract/deliver, /cli/contract/accept, /cli/contract/reject, /cli/contract/resolve, /cli/contract/cancel
• /cli/contract/list-matching, /cli/contract/show

Each page: flag-by-flag table, example invocation with copy-pasteable output, common errors.

SDK reference (new pages)

• /sdks/typescript/bounty-client — full method reference for BountyClient
• /sdks/typescript/contract-client — full method reference for ContractClient
• /sdks/typescript/wire-format-types — TypeScript types reference (auto-gen from typedoc)
• /sdks/typescript/utilities — BountyId.derive, ContractId.derive, hash helpers

Worked-example walkthroughs (two)

• /guides/post-a-bounty-and-earn — end-to-end: register schema → post bounty (CLI) → attest (SDK) → claim (CLI). Composes the chain + CLI + SDK + API surfaces into one narrative.
• /guides/post-a-contract-and-receive-deliverable — end-to-end: post contract (CLI) → worker commits + delivers (SDK) → accept (CLI). Includes the named-arbiter dispute path as a sub-section.

Concept pages

• /concepts/bounty-vs-contract — when to use which primitive (covers the cut-line from the contract primitive RFC)
• /concepts/evaluation-pool — the neutral verification pattern from chain#534 (when chain#535 ships)

Estimated effort

1 session for the reference pages (mechanical, typedoc + endpoint schemas drive most of it). 1 session for the walkthroughs (more thought-out narrative).

Acceptance

• All reference pages live + linked from the nav
• Walkthroughs tested end-to-end against chain v0.4.0 devnet (or testnet when it cuts)
• "Edit on GitHub" works for every page
• Code blocks are copy-pasteable + runnable
• Cross-links to the RFCs (bounty-marketplace.md, contract-primitive.md, prompt-evaluation-pool.md) in the chain repo

Out of scope (separate follow-ups)

• Video walkthroughs (post-mainnet)
• Auto-generated TypeScript reference from typedoc (separate infrastructure work)
• Translated docs (post-mainnet)