feat(tokens): cap the built-in token table at 500 entries — frees 23,104 B flash

[BitHighlander]

tokens is the single largest read-only symbol in the ARM image: 31,104 bytes for 1,945 entries — bigger than MessagesMap (27,264) or the BIP-39 wordlist (8,196).

tokens   31,104 -> 8,000 B   (500 entries x 16)
saved    23,104 B of flash

Why a budget, not a bigger table

The vetted source is a stale snapshot and cannot be made current by shipping more of it. Measured against ethereum-lists as pinned:

• 1,924 of 1,945 entries are Ethereum mainnet. Optimism has 2, Polygon 3, BSC 3. Base and Arbitrum have no directory at all.
• Absent entirely: UNI, AAVE, stETH, wstETH, rETH, cbETH, PEPE, and every modern stablecoin — FRAX, LUSD, PYUSD, crvUSD, USDe.
• ARB resolves to 0xafbec4d6…, a 2017 token called "ARBITRAGE". Arbitrum's real ARB (0xB50721BC…) is not in the table.

So the long tail is not coverage — it is 2017-era ICO tokens occupying flash while the assets users hold are missing. USDC, USDT, DAI, WETH, WBTC, LINK are present and correct, and those are what the budget protects.

Policy

1. Budget: 350 from ethereum-lists + 150 from the uniswap list.
2. Priority symbols first — stablecoins, then majors.
3. A priority symbol is taken only when the source gives exactly one address. Two entries sharing a symbol is how a scam token inherits a real one's label. Ambiguous symbols are dropped and reported at build time.
4. Remainder filled in the existing deterministic order, so output stays reproducible and diffable.

No address is written in the policy — symbols are matched against the vetted source. A hand-typed address in a token table is a mislabelling defect waiting to happen.

Two groups pinned for structural reasons, both named

• REQUIRED_BY_COINS (26) — tickers declares with a contract address. correctly failed when the first cut dropped them: the device would advertise a coin it cannot name. They are 2017 tokens and should go next, but that cut belongs in — itself a 23,808-byte symbol.
• REQUIRED_BY_TESTS (1) — ADT, which a test uses as its canonical "known ERC-20" while asserting a hardcoded signature. A fixture should not pin firmware flash; migrating that test to USDC retires it.

439/439 · full pyk 632 passed / 25 skipped / 0 failed · ARM SRAM unchanged at 18,172 B