feat(observability): add alert rule toggle APIs

[ThisIsMani]

Summary

This is the stacked Rule enable/disable toggles port for the observability plane. It moves only the named domain's mutable-state list/set operations behind authenticated typed APIs and preserves rule identity, disabled-rule behavior, and portal-compatible set responses.

Depends on base PR #14268 (feat/observability-alert-blacklist), which is also the target branch for this PR.

APIs

• GET /alerts/rule-toggles
• PUT /alerts/rule-toggles/{rule_id}
• Both use X-Internal-Api-Key authentication and typed JSON models.
• PUT preserves the portal response shape: { "ok", "id", "is_enabled" }.

Schema and persistence

• Adds the reversible alert_rule_toggles PostgreSQL migration.
• Adds grouped alert-manager API models, Diesel models, schema, and Diesel DSL list/upsert queries.
• Preserves deterministic listing and rule_id as the natural identity.

Tests

• cargo fmt --all -- --check
• cargo check -p observability
• cargo test -p observability --test rule_toggles (4 passed; 1 database test ignored in the no-database run)
• cargo test -p observability --test blacklist --test thresholds (12 passed; 2 database tests ignored)
• cargo test -p observability rule_id_is_trimmed_and_blank_is_rejected
• diesel migration run --locked-schema against a temporary local PostgreSQL database
• diesel migration redo --locked-schema --all against a temporary local PostgreSQL database
• OBSERVABILITY_TEST_DATABASE_URL=... cargo test -p observability --test rule_toggles postgres_repository_replaces_and_lists_toggles -- --ignored
• git diff --check

Analytical/business reads and users are unchanged. No analytics or user endpoints are added or moved.

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
crates/observability/src/db.rs	8% smaller
crates/observability/tests/blacklist.rs	1% smaller
crates/observability/tests/thresholds.rs	1% smaller
crates/api_models/src/observability/alert_manager.rs	0% smaller
crates/api_models/src/observability/alert_manager/rule_toggles.rs	0% smaller
crates/diesel_models/src/observability/alert_manager.rs	0% smaller
crates/diesel_models/src/observability/alert_manager/rule_toggles.rs	0% smaller
crates/diesel_models/src/observability/query/alert_manager.rs	0% smaller
crates/diesel_models/src/observability/query/alert_manager/rule_toggles.rs	0% smaller
crates/diesel_models/src/observability/schema.rs	0% smaller
crates/observability/migrations/2026-09-15-000004_create_alert_rule_toggles/down.sql	Unsupported file format
crates/observability/migrations/2026-09-15-000004_create_alert_rule_toggles/up.sql	Unsupported file format
crates/observability/src/core.rs	0% smaller
crates/observability/src/core/rule_toggles.rs	0% smaller
crates/observability/src/db/rule_toggles.rs	0% smaller
crates/observability/src/domain_models.rs	0% smaller
crates/observability/src/domain_models/rule_toggles.rs	0% smaller
crates/observability/src/routes.rs	0% smaller
crates/observability/src/routes/app.rs	0% smaller
crates/observability/src/routes/rule_toggles.rs	0% smaller
crates/observability/tests/rule_toggles.rs	0% smaller

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Reject blank updater identities

When a caller sends "updated_by": " ", this value is persisted and later returned as the audit identity, leaving the toggle change unattributed. The sibling threshold API explicitly rejects blank updated_by values, so validate this field with trim().is_empty() before constructing the row.

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[ThisIsMani]

Fixed in the latest tree: whitespace-only updated_by is rejected before persistence, with route coverage confirming an invalid request does not overwrite stored state.

[ThisIsMani]

Fixed in the latest tree: blank or whitespace-only updated_by values are rejected before persistence, with route and domain coverage.