fix(dns): pair retained values before position in the set plan

[AshutoshMore142k4]

Summary

• plan_set paired existing records to --data values purely by position, so a value that was staying in the set could get paired with a different record and re-created. v3 keys record identity on (name, type, data), so that create fails with DUPLICATE_RECORD — and apply_replace deliberately keeps the old record when its create fails, while the surplus Delete later in the plan still runs unconditionally.

• Net effect on a narrowing set: given www A {1.2.3.4, 5.6.7.8}, running

  gddy dns set example.com --type A --name www --data 5.6.7.8
  

  planned Replace{r1 → 5.6.7.8}, Delete{r2}. The replace's create collided with r2's still-live 5.6.7.8, so r1 was kept; the delete then removed r2. The zone ended up holding 1.2.3.4 — the value the user asked to drop — with 5.6.7.8 gone. The command does exit non-zero, but the zone is already inverted by then.

• A pure reorder (--data 5.6.7.8 --data 1.2.3.4 against the same zone) is the same root cause with a milder symptom: both replaces fail as duplicates and the command errors having changed nothing.

• Fix: pair each desired value with the record that already holds it first, then pair whatever is left by position exactly as before. A value that stays in the set is therefore never re-created, so the collision can't arise. plan_set now takes (record_id, current value) so it can see content; ordering of the emitted plan (replaces → deletes → creates) is unchanged.

Ordering deletes before creates would also dodge the collision, but it opens a window where the name resolves to nothing — so this keeps the existing create-then-delete shape.

Test plan

• cargo check --workspace
• cargo fmt --check
• cargo test --workspace — 780 passed
• ./rust/scripts/check-module-size.sh
• cargo clippy --workspace --all-targets -- -D warnings — clean for this change. (Unrelated pre-existing note: on a Windows host it errors on an unused use super::* in extension/security/file_discovery.rs, whose only two tests are #[cfg(unix)], so that test module compiles empty there. CI on ubuntu is unaffected.)
• Four new plan_set cases: the narrowing case above, a pure reorder, a mixed keep-one/replace-one, and duplicate --data values pairing to distinct records
• Existing plan_set and dry_run_set_preview tests updated for the new parameter shape and still assert the same plans

[Copilot]

🟡 Changes recommended

Retained records must be matched using full type-specific identity to avoid incorrect replacement and deletion.

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Pull request overview

This PR updates DNS set reconciliation to preserve retained records before positional replacement, preventing duplicate-create failures during narrowing and reordering.

Changes:

• Updates plan_set pairing and planner inputs.
• Updates command and dry-run tests.
• Adds regression coverage for narrowing, reordering, mixed changes, and duplicates.

File summaries

File	Summary
rust/src/dns/set/plan.rs	Implements retained-value pairing and tests; critical issue remains because matching ignores type-specific identity fields.
rust/src/dns/set/outcome.rs	Updates dry-run plan tests for the new planner inputs.
rust/src/dns/set/mod.rs	Supplies record values to planning; the same critical full-identity matching issue remains.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 2
• Review effort level: Lite

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