feat(membership): refuse collapsing targets into entity or project

[seonghobae]

Language, episode, template, department, and opportunity-pool memberships stay typed (ADR 0003). They cannot collapse into the entity/project pair stored by migration 0006. Recovery is the computed share of recovered target kinds that match known truth versus treating every target as an entity.

Local gates on this head:

• cargo test -p membership_target --all-targets GREEN after RED (package did not exist)
• clippy -D warnings PASS
• workspace contract PASS
• docstring contract PASS
• lines 15/15; nightly-2026-08-01 branches 8/8

Does not allocate migration 0008. Does not recreate membership_core, role_contradiction, support_edge, or in-flight crates.

Keep this PR draft. Preferred merge remains #46 only when exact-head required Checks pass and a qualifying independent (non-Cursor/CodeRabbit) APPROVE exists. OpenCode CHANGES_REQUESTED on #46 is a stale coverage-evidence race on a now-green head — do not empty-commit.

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 646fc8d4-8d74-4221-b997-0f1fc322be70

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}