refactor(threads, tool_timeout): extract pure helpers for testability

[jwalin-shah]

Summary

Pure refactor — no behavior change. Extracts two bodies of pure logic into isolated, unit-testable units:

• threads::title (new module) — moves THREAD_TITLE_* constants and the title_log_fingerprint, is_auto_generated_thread_title, collapse_whitespace, sanitize_generated_title, build_title_prompt helpers out of threads::ops so the parsing/sanitisation rules can be exercised without Config, provider runtime, or RPC wiring.
• tool_timeout::parse_tool_timeout_secs — splits the env-var parsing out of resolved_secs so it's pure (no OnceLock, no process env mutation) and every branch can be tested.

threads::ops now imports the helpers from threads::title and keeps the same call sites / call signatures; tool_execution_timeout_secs() behavior is preserved (resolved_secs now delegates to the pure parser).

Tests added

• threads::title — 24 tests covering fingerprint stability, all accept/reject paths for the auto-generated placeholder shape (single/two-digit day + hour, AM/PM, user-renamed titles, malformed minutes, numeric month, missing suffix), whitespace collapse edge cases, sanitiser rules (quote/backtick stripping, trailing punctuation, first non-empty line selection, empty handling, char-count truncation including multi-byte UTF-8), and prompt construction.
• tool_timeout — 7 tests covering default fallback, non-numeric values, zero, above-max, negative/signed, valid boundary (1 and MAX_SECS), and midrange.

Validation

• cargo test -p openhuman --lib threads::title → 24 passed
• cargo test -p openhuman --lib tool_timeout → 7 passed

Risk

Minimal. Logic is byte-for-byte identical to what was inline; only the module boundary changed. Constants are re-exported from the new module and referenced by their original names in threads::ops.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: ba784268-d738-4b95-8dfe-a49666af90fc

📥 Commits

Reviewing files that changed from the base of the PR and between b3b451f and 7cc42ab.

📒 Files selected for processing (4)

• src/openhuman/threads/mod.rs
• src/openhuman/threads/ops.rs
• src/openhuman/threads/title.rs
• src/openhuman/tool_timeout/mod.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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