feat(cli): ccv migrate export/inspect commands

[tt-cll]

Description

ccv migrate export and ccv migrate inspect in the verifier and executor images — the operator-facing half of the migration, replacing the manual chainlink keys ... list/export steps so nothing is transcribed by hand.

• export: preflights the node's job shape, resolves the EVM bundle and the chain's enabled account itself, exports under a generated password, verifies the exports decode to the registered identities, and writes ready-made [key_import] snippets with expected_id filled in.
• inspect: prints the identity a mounted export carries, so a wrong-node mount is caught before boot.
• Procedure doc updated to the tool flow (steps 1 and 3), with a who-does-what split (operator: steps 1–5; Chainlink Labs: JD record, topology, specs) and an in-flight-transactions note for the node stop.

Testing

Unit tests for the credentials file reader; the export path itself is covered by the shared package's tests and the devenv e2e.

Checklist

• Breaking changes documented in changelog (see changelog directory)
• Cross link related PRs (in this or other repositories)

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