docs: add Stellar, Filecoin, Cronos and Klaytn, plus historical balance for five chains

[buddies2705]

Follow-on to #251. These two commits were pushed after #251 merged, so they were left behind on the old branch. Cherry-picked here onto the updated main. Same thing happened between #250 and #251 — worth a squash-and-hold before the next merge.

Four new chains — 22 queries

All V1-only, all authored from scratch, since none had a docs page carrying IDE links.

Chain	Queries
Stellar	6 — ledgers, transactions, payments, DEX trades, account balances, liquidity pool trades
Klaytn	7 — the V1 EVM set including DEX trades and top DEXs
Cronos	5 — no DEX set, see below
Filecoin	4 — tipsets, messages, transfers, address balance

Every query was executed before being saved. Reaching 22/22 took four rounds, and each failure was a shape that looks right and isn't:

• Stellar's block is a scalar ledger number, not an object. block { height } fails, and sorting must use desc: "block".
• Filecoin messages use amount and method { name }, not value / method.
• Cronos has no dexTrades table (ClickHouse Code 60), so it ships without the DEX queries exactly as Celo does.
• Query memory limits differ per chain and per cube. Cronos blocks needs a date bound, and Stellar transactions and payments need a window about a day wide where a week is fine elsewhere. Every bound is a $since variable so it can be moved.

Historical balance for five chains

Balance is asked of every chain in both directions, so a chain with only the current side is half-covered. Adds the historical side for Cronos, Klaytn, Avalanche, Stellar and Filecoin, computed as everything received minus everything sent up to a date.

Balance gaps are now 6 chains, down from 16 when this work started.

The example address for each is discovered from a real recent transfer on that chain rather than guessed, so the saved query returns rows.

llms.txt

New Endpoints, chains and datasets section: which chains are on V2 versus V1, that root capitalisation marks the version (EVM( is V2, ethereum( is V1), that Ethereum, BSC, Tron and Polygon are migrating to V2, and what realtime / archive / combined mean — plus links to the dataset and retention pages. The starter query and subscription trees are now listed under "Start here".

Verification

690 query entries across 32 groups, 383 stream entries across 17. All eleven gates pass and the production build is clean.

All 87 queries authored across this work were re-executed read back out of the database: 79 run, 6 retired, 2 reported failing.

Both reported failures were checked rather than believed, and both are transient: Avalanche smart-contract-events passes on retry, Klaytn latest-blocks passes with a longer timeout. These V1 chains are slow enough under load that a single-shot audit invents failures, so the round-trip audit now retries before reporting.

Two more V1 rules learned here and now encoded in the audits:

• Sorting by a field requires selecting it. desc: "block.height" without block { height } returns "Can't use block.height in sorting" — this silently broke an address finder on all five chains.
• The chain-scope gate had no rule for Filecoin, so it was passing vacuously. Fixed and verified to discriminate.

Known gaps

• 6 chains still lack one side of balance: Solana, Robinhood, BSC and Cardano have no historical, Ripple no current, Algorand neither. Solana's historical balance query exists but is filed under Transfers.
• 432 entries would benefit from a dataset comment pointing at archive / combined; only 109 are on our account, so the rest currently carry the guidance in tooltips instead.

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