Add mutable options and TTL helpers to C API

[jurmous]

Summary

• add new C API typedefs and functions for mutable options, table filters, persistent cache, custom logger callbacks, env factories, and TTL DB wrappers
• implement the new APIs in db/c.cc including ownership tracking, table filter bridging, persistent cache creation, mutable option parsing, and TTL helpers
• extend c_test with coverage for the new APIs including mutable options parsing, logger lifecycle, table filter wiring, env factories, persistent cache, and TTL wrappers

Testing

• make -j8 c_test

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https://chatgpt.com/codex/tasks/task_e_68e63c1866648321ac47a4ba13a4b795