fix(ai-monitoring): Raise conversation title max_tokens to 192

[sehr-m]

_generate_title_with_legacy_seer asks Seer for structured output with max_tokens=64 and reasoning="off" (so thinking_budget=0 and no padding) — a hard 64-token ceiling on visible output. On noisy input the model over-generates, the JSON never closes, and the response is unparseable. All three retries re-send an identical request at temperature=0.2, so they truncate identically, and llm_total_models: 1 means there is no fallback model behind it.

seer.llm.structured_invalid over the last 24h, grouped by finish_reason:

finish_reason	count
max_tokens	1,819
stop	7
unknown	1

Truncation is ~99.6% of direct structured failures. 192 leaves ~180 tokens for the title after the JSON envelope, against a happy path of ~25.

Notes:

• Paired with getsentry/seer#7944, which fixes the identical 64 in seer's conversation_title one-shot handler. The ai-monitoring.conversation-title-generation.oneshot-rollout-rate option defaults to 0.0, so all real traffic is currently on this legacy path — but the one-shot path inherited the same bug and needs both.
• User-visible impact of the failure is cosmetic: generate_conversation_title falls back to fallback_title_from_message, so a conversation shows a truncated first message instead of a real title. The cost is ~3,700 wasted flash-lite calls/day and ~29k Sentry error events (SEER-945), which is the largest issue in the seer project.
• This does not close SEER-945 on its own. The raise in seer's llm_proxy.py:120 still turns any remaining parse failure into a 500, and other structured callers have their own budgets.

[chromy]

lgtm! fyi @vgrozdanic

[vgrozdanic]

thank you for fixing this 🙏

We can merge this today, but on Monday, i am planning to clear all of these legacy seer API code since we migrated to oneshot Seer API.

I'll leave it up to you if you want to merge this today, or just close the PR and on Monday i clean up all of this "old" code, it's already not being called as we are on 100% rollout of the new path that is using oneshot