…#21513)

## Problem

The Hive `legacy-cancun` BlockchainTests suite intermittently fails 4
tests with `client did not start: timed out waiting for container
startup`:

- `walletReorganizeOwners_{Cancun,Istanbul,London,Paris}`

(e.g. [this
run](https://hive.ethpandaops.io/#/test/generic/1779833679-c7f17208e0b5dbf959b3448bbdaed60e)).
They took ~181s, just over Hive's 180s container-startup timeout. The
same test on other forks (Shanghai/Berlin) and `ForkStressTest_*` sit at
146–150s — right at the cliff.

## Root cause

The `import` command documents multi-file support:

```
USAGE: erigon import [command options] <filename> (<filename 2> ... <filename N>)
```

but `importChain` only processed `cliCtx.Args().First()`, silently
ignoring the rest. That forced Hive's erigon entrypoint into a
one-process-per-block-file loop. For `walletReorganizeOwners` (235 block
files) that is 235 full erigon startups — measured at ~0.5s/process ×
261 = 145s of pure startup, while actual block execution is ~40ms each.
go-ethereum has no such problem: its entrypoint imports every block in
one `geth import` invocation.

## Fix

Iterate every file argument in a single process, tolerating per-file
failures when several files are given (matching go-ethereum). This lets
the hive entrypoint import all blocks in one invocation, collapsing
hundreds of process startups into one (~150s → ~10s).

It also force-disables the embedded MCP server for the one-shot import
(`--mcp.disable`, alongside the existing NAT / downloader /
external-consensus disables) — a batch import has no use for it.

## Companion change (required)

The hive entrypoint must pass all block files in one invocation:
ethereum/hive#1519. Order matters — the hive change depends on this one
(on an old erigon, `import /blocks/*` would import only the first
block).

## Testing

- New unit tests (`import_cmd_test.go`): all-files iteration, per-file
failure tolerance, single-file error surfacing.
- Real-binary check: `erigon import a.rlp b.rlp` now attempts **both**
files in one process (previously stopped after the first).
- `make lint` clean; `make erigon integration` builds.

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Giulio Rebuffo <111551070+Giulio2002@users.noreply.github.com>