CLI: Add --export-encoding instruction-list mode

[aoikurokawa]

Summary

• Adds instruction-list as a new value for the --export-encoding CLI option, alongside the existing none|utf8|base58|base64 choices.
• When selected, the CLI prints a human-readable view of each transaction (program address, accounts with writable/signer flags, and base58-encoded instruction data) instead of the raw encoded transaction bytes.
• Default behavior is unchanged: without --export-encoding instruction-list, output remains exactly the raw encoded transaction so downstream tooling that consumes the bytes is not affected.

Motivation

Per review feedback, the instruction-list view is useful for humans inspecting what a --exported transaction will do, but it pollutes output for users who only need the raw transaction bytes (e.g. piping into another tool). Making it a separate export mode lets each use case stay clean.

Changes

• clients/js/src/cli/options.ts: introduce ExportEncoding = Encoding | 'instruction-list', add instruction-list to --export-encoding choices, and update the parser.
• clients/js/src/cli/utils.ts: branch in exportTransactionPlan — print the instruction list when instruction-list is selected, otherwise print only the encoded transaction (no instruction list).
• clients/js/src/cli/logs.ts: logExports accepts the new ExportEncoding type and renders "... as an instruction list" vs. "... in <encoding>".

node bin/cli.cjs write \
    idl ... \
    --buffer ... \
    --export ... \
    --export-encoding instruction-list \
    --close-buffer ...