List all ready hearings, paginated + filterable

Query params:

• committee_thomas_id (optional) — filter to one committee
• search (optional) — match hearing title, committee, linked bills, witnesses, or transcript text
• chamber (optional) — house | senate
• has_bills (optional, "true"/"false") — only hearings with linked bills
• tracked_only (optional, "true") — only hearings linked to bills the caller tracks
• when (optional) — upcoming | past_30d
• date_from, date_to (optional, ISO YYYY-MM-DD)
• limit (default 50, max 100)
• offset (default 0)