chore: add PHPDoc descriptions to types and request classes

Enrich the SDK's inline documentation by adding class-level PHPDoc
blocks and property-level descriptions across a large set of types and
request DTOs. No public API signatures, method names, or property names
were changed.

Key changes:
- Add class-level PHPDoc summaries to ~40 types (e.g., `Assistant`, `Call`, `Edge`, `CompliancePlan`, `BackoffPlan`, `CreateWorkflowDto`, and many more)
- Add inline `@var` descriptions to previously undocumented properties (e.g., `firstMessageInterruptionsEnabled`, `compliancePlan`, `keypadInputPlan`, `baseDelaySeconds`, `excludedStatusCodes`)
- Condense multi-line PHPDoc blocks into single-line `@var` descriptions for consistency (e.g., `BackoffPlan::$excludedStatusCodes`, `CustomerSpeechTimeoutOptions::$triggerResetMode`)

🌿 Generated with Fern

Author: fern-api[bot]

changelog.md

@@ -1,3 +1,5 @@
+## [2.0.1] - 2026-07-27
+
 ## 2.0.0 - 2026-06-24
 ### Breaking Changes
 * **`CartesiaExperimentalControlsSpeedZero`** has been renamed to `CartesiaSpeedControlZero`. Update any references to this enum in your code to use the new name.