feat[py]: add timeouts, base_url, cookies, follow_redirects; unify Response types

[deedy5]

Summary

• New timeout options: Added connect_timeout and read_timeout parameters to client initialization and per-request configuration
• Base URL support: Added base_url parameter for resolving relative paths
• Client cookies: Added cookies parameter to initialize clients with pre-set cookies
• Per-request redirect control: Added follow_redirects parameter to override client defaults per-request
• Unified Response types: Merged Response/StreamResponse and AsyncResponse/AsyncStreamResponse into single unified types with a streaming flag
• Redirect policy: Exposed set_redirect_policy() method on Client for runtime redirect configuration
• Updated docs, examples, tests, and type stubs to reflect all API changes

Changes by crate

primp-reqwest

• Add ReadTimeout config type
• Add read_timeout() method to RequestBuilder
• Add set_redirect_policy() to Client

primp

• Expose set_redirect_policy() on Client wrapper

primp-python

• Add connect_timeout, read_timeout, base_url, cookies, follow_redirects parameters
• Unify Response/StreamResponse into single Response type
• Unify AsyncResponse/AsyncStreamResponse into single AsyncResponse type
• Update type stubs, docs, examples, and tests