stats/status-line resolve analytics DB inconsistently with dispatch (config db_path ignored)

[vishnujayvel]

Problem

Found while live-verifying the cost-tracking writer (#103). Commands resolve the analytics DB path inconsistently:

• dispatch (the writer) uses config.Analytics.DBPath from the loaded config.
• stats uses a --data-dir flag that defaults to ~/.hookwise/analytics.db (DefaultDBPath) and does not read config.Analytics.DBPath or honor HOOKWISE_STATE_DIR.

So if a user sets a custom analytics.db_path, dispatch writes cost into the custom DB but stats reads the default DB and shows $0. (Repro: set analytics.db_path to a temp file, dispatch a Stop with a transcript → custom DB gets total_today/estimated_cost_usd, but hookwise stats shows $0 from ~/.hookwise/analytics.db.)

Default config (no custom db_path) is unaffected since both land on ~/.hookwise/analytics.db.

Likely also affected

The cost status-line segment / renderCostSegment path — confirm it resolves the DB the same way dispatch does.

Fix direction

Make stats (and the status-line cost path) default dataDir from the loaded config's Analytics.DBPath (falling back to DefaultDBPath) so reader and writer agree. Same class as #104 (doctor reads real ~/.hookwise).

Severity: low-medium (silent $0 under custom db_path), but it undermines confidence in the brand-new cost feature.