fix(types): document cookie secure and httpOnly defaults as true

[Hashim1999164]

Summary

• Re-declare httpOnly and secure on CookieOptions with @default true JSDoc so IDE tooltips match runtime and README behavior.
• Previously these fields were inherited from @fastify/cookie CookieSerializeOptions, which documents defaults as false.

Fixes #299

Test plan

• npm run test:typescript
• npm run test:unit (100% coverage)

[Tony133]

The fix looks great! Could you also update the type test file to include assertions for httpOnly and secure on CookieOptions?

see here: https://github.com/fastify/session/blob/main/types/index.tst.ts#L59

- const cookieMaxAge: CookieOptions = {}
- expect(cookieMaxAge.maxAge).type.toBe<number | undefined>()

+ const cookieOptions: CookieOptions = {}
+ expect(cookieOptions.maxAge).type.toBe<number | undefined>()
+ expect(cookieOptions.httpOnly).type.toBe<boolean | undefined>()
+ expect(cookieOptions.secure).type.toBe<boolean | 'auto' | undefined>()

[Hashim1999164]

Updated types/index.tst.ts with assertions for httpOnly and secure on CookieOptions as requested.

[Tony133]

lgtm