docs(providers): map internal target naming migration

[christso]

Summary

• Adds a self-contained implementation map for hard-migrating internal target-era provider names to provider terminology.
• Captures Promptfoo provider-label evidence and classifies remaining target-era terms across core, CLI, SDK, artifacts, docs, scripts, and tests.
• Creates/updates follow-up Beads av-kfik.53.1 through av-kfik.53.7 for executable hard-migration slices with no compatibility aliases by default.

Validation

• git diff --cached --check before commit
• bd dep cycles
• No builds/tests run: research/docs-only audit work, no implementation code changed.

Bead: av-kfik.53

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