docs: add initial changelogs for Flipper packages

Add CHANGELOG.md files for the following packages to document
their initial releases, features, and supported functionality:

- @flippercloud/flipper: TypeScript feature flag library
- @flippercloud/flipper-cache: generic cache wrapper with TTL
- @flippercloud/flipper-redis: Redis adapter for feature flags
- @flippercloud/flipper-sequelize: Sequelize adapter for RDBMS

This provides release notes and feature lists for new users and
improves discoverability and maintenance tracking for the
codebase.

Author: jonmagic

packages/flipper-cache/CHANGELOG.md

@@ -0,0 +1,11 @@
+# @flippercloud/flipper-cache
+
+## 0.0.1
+
+Initial pre-release of generic cache wrapper for Flipper TypeScript adapters.
+
+### Features
+
+- Read-through cache support
+- Write-through cache support
+- Configurable TTL and cache layers

packages/flipper-redis/CHANGELOG.md

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+# @flippercloud/flipper-redis
+
+## 0.0.1
+
+Initial pre-release of Redis adapter for Flipper feature flags.
+
+### Features
+
+- Redis adapter for feature flag storage
+- Support for ioredis client
+- TTL management

packages/flipper-sequelize/CHANGELOG.md

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+# @flippercloud/flipper-sequelize
+
+## 1.0.0
+
+Initial release of Sequelize adapter for Flipper feature flags.
+
+### Features
+
+- Sequelize adapter for relational databases
+- Support for SQLite, PostgreSQL, MySQL, and other Sequelize-supported databases
+- Full feature flag management through database

packages/flipper/CHANGELOG.md

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+# @flippercloud/flipper
+
+## 1.0.0
+
+Initial release of Flipper feature flags for TypeScript/JavaScript.
+
+### Features
+
+- Feature flag evaluation engine
+- Support for actors, groups, percentages, and expressions
+- Memory adapter for development
+- TypeScript support with full type safety