fix(flexible/databases): Database.activated should be activatedOn (silent data drop)

[joshrotenberg]

Summary

Database.activated is named incorrectly. With #[serde(rename_all = "camelCase")] it serializes as activated, but the API returns activatedOn. The field silently deserializes to None on every response.

Expected behavior

The activation timestamp from the Cloud API is preserved on the typed Database model.

Actual behavior

• src/flexible/databases.rs:928: pub activated: Option<String> → wire key activated
• API actually returns activatedOn (a format: date-time string)
• Result: silently dropped on every list/get response.

Impact

Any caller using database.activated for ordering, filtering, age computation, or display sees None for every database. No error is surfaced.

Relevant code

• src/flexible/databases.rs:928
• Spec: tests/fixtures/cloud_openapi.json — Database schema, property activatedOn (format: date-time)
• See docs: OpenAPI spec deltas - fields missing from official spec #40 — Database row in the deltas tracking table

Suggested fix

Either rename the field or add a serde rename:

```rust
#[serde(rename = "activatedOn")]
pub activated_on: Option,
```

Consider whether to use chrono::DateTime<Utc> or time::OffsetDateTime here for type-safe handling of format: date-time. If keeping String for now, document it in the field doc.

Acceptance criteria

• Field name and serde wire-key match activatedOn
• Mock test asserts the field is populated when the response includes activatedOn
• Migration note in CHANGELOG (renamed public field)

References

• Surfaced in 2026-05 review (axis A2 — type correctness, P0 chore: release v0.9.0 #4)
• Related: docs: OpenAPI spec deltas - fields missing from official spec #40 (spec deltas tracking)