Feat/stellar sponsored batch send (#146)

* docs: add Python quickstart for Stellar stealth payments

Covers the full flow for Python 3.11+ backends that want to talk to
Wraith contracts without the TypeScript SDK:

- guides/quickstarts/python.mdx (new)
  - pip install stellar-sdk + cryptography only
  - wraith_crypto.py inline utility: scan-key derivation via SHA-256
    domain separation, X25519 ECDH, ed25519 point addition, view-tag
    prefilter, sign_with_scalar (RFC 8032 compatible raw scalar signing)
  - Fetch WRAITH_ANNOUNCEMENT events from Soroban RPC (getEvents + XDR decode)
  - scan_announcements with view-tag prefilter (~255/256 skip rate)
  - Send: createAccount activation + Soroban announcer invocation
  - Spend: withdrawal tx signed with raw stealth scalar
  - All Python fences marked no-check for the TS snippet gate
  - Targets futurenet; notes testnet contract IDs for live testing

- sdk/overview.mdx: cross-link to Python quickstart under Next Steps

- docs.json: Quickstarts nav group added above Guides in the Guides tab

* docs(stellar): add sponsored-batch-send guide for paymaster airdrop pattern

Add guides/stellar/sponsored-batch-send.mdx covering:
- BeginSponsoringFutureReserves + batch send + EndSponsoringFutureReserves pattern
- Reserve vs fee cost model with AccountMerge refund lifecycle
- End-to-end airdrop example for 100 stealth recipients (chunked at 24/tx)
- Failure modes: auth revocation, insufficient reserves, missing EndSponsoring
  signature, and trustline missing inside sponsorship window
- Futurenet testing section

Update docs.json: add nav entry in Guides > Operations group.
Update guides/stellar-fees.mdx: cross-link to new guide in See Also.

All 10 TypeScript snippets pass tsc --noEmit (check:snippets CI).

* fix(docs): resolve merge-artifact duplicate pages key in Quickstarts group

The auto-merge of develop into feat/stellar-sponsored-batch-send produced
an invalid docs.json: the Quickstarts group ended up with two separate
"pages" keys (python from this branch, rust from develop) with no comma
between them. Merged both entries into a single pages array.

Fixes: pnpm run check:nav-coverage JSON parse error at position 3128.

---------

Co-authored-by: musay <ochoalaurie@gmail.com>

Author: Mathew2k-hash

docs.json

@@ -171,6 +171,7 @@
               "guides/stellar-custom-assets",
               "guides/stellar/stellar-liquidity-pool-swap",
               "guides/stellar/stellar-path-payment",
+              "guides/stellar/sponsored-batch-send",
               "guides/stellar/passkey-signing",
               "guides/stellar/stellar-quickstart",
               "guides/stellar/wraith-names-lifecycle",

guides/stellar-fees.mdx

@@ -172,6 +172,7 @@ To ensure smooth operations in production apps, implement these heuristics:
 
 ## See Also
 
+- [Sponsored Batch Send](/guides/stellar/sponsored-batch-send) — paymaster covers 1 XLM reserves for every new stealth recipient; ideal for airdrops and payroll
 - [Reflector Oracle Integration](/guides/integrations/reflector) — plug Reflector into Wraith flows for inline fiat conversion alongside fee estimation
 - [Spectre + Stellar Cookbook](/guides/spectre-stellar-cookbook) — production recipes for Stellar agents
 - [Stellar Payment Links](/guides/stellar-payment-links) — generate payment links with fiat amounts