feat(v0.5.11): band conditions scheduled broadcaster (3x/day HF propagation)

First clock-driven broadcaster in meshai, distinct from the v0.5.8b/v0.5.9/v0.5.10 event-driven adapters. The same persistence + dispatcher + cold-start patterns apply, but the trigger is the wall clock at 06:00 / 14:00 / 22:00 Mountain Time (default; GUI-configurable per Rule 17).

Components: (1) meshai/notifications/scheduled/band_conditions.py with BandConditionsScheduler (asyncio loop, mirrors the existing DigestScheduler shape), compute_band_ratings() with two-tier data sourcing -- (a) latest swpc_kindex + swpc_alerts F10.7 rows from persistence within the last 6h, (b) HamQSL.com solarxml.php fallback when SWPC is stale or incomplete, (c) silent skip when both fail, format_band_conditions_wire() multi-line MEDIUM output (~115-120B). (2) v3 schema migration adding band_conditions_broadcasts(broadcast_id PK AUTO, sent_at, scheduled_for UNIQUE, ratings_json, source). UNIQUE(scheduled_for) enforces per-slot dedup so a retry storm cannot double-broadcast. (3) Dispatcher.dispatch_scheduled_broadcast() bypasses the toggle / rules / freshness-gate pipeline but DOES honour the v0.5.8b cold-start grace -- first scheduled broadcast within the grace window after meshai starts is suppressed, mesh_broadcasts_out audit row only inserted on actual delivery. Channel selection routes through the rf_propagation toggle\'s broadcast_channel since band conditions IS RF-propagation info. (4) NotificationsConfig gains band_conditions_enabled (default true), band_conditions_schedule (list of HH:MM strings, default ["06:00","14:00","22:00"]), band_conditions_tz (default "America/Boise" so DST handles automatically). (5) Notifications.tsx grows a Band Conditions card between Cold-Start Grace and Master Toggles with the enable toggle + 3 TimeInput slots + a one-liner explaining the source priority. (6) build_pipeline + start_pipeline spawn the BandConditionsScheduler alongside the existing DigestScheduler -- best-effort, scheduler failures must NOT break notifications startup.

Wire format examples (multi-line, all under 130B target):

  ☀️ Day Propagation
  📡 Band Conditions:
  80-40m: 🟡 Fair
  30-20m: 🟢 Good
  17-15m: 🟢 Good
  12-10m: 🟡 Fair

  🌞 Day Propagation  (14:00 slot when storm onset, Kp=6 SFI=110)
  📡 Band Conditions:
  80-40m: 🔴 Poor
  30-20m: 🔴 Poor
  17-15m: 🔴 Poor
  12-10m: 🟡 Fair

  🌙 Night Propagation  (22:00 slot, recovery, Kp=4 SFI=120)
  📡 Band Conditions:
  80-40m: 🟡 Fair
  30-20m: 🟡 Fair
  17-15m: 🔴 Poor
  12-10m: 🔴 Poor

Tests: was 686 (v0.5.10 baseline), now 704 (+18 net new -- quiet/storm condition ratings, HamQSL XML parse fallback, both-fail silent-skip path, is_day_slot per HH:MM, wire format for all 3 slot variants, byte-size guard, 6-line shape, fire_slot record row, dedup via UNIQUE constraint, silent-skip path, slot_epoch DST alignment summer + winter). Synthetic 24h probe verified the 3 expected slots fire correctly with quiet/storm/recovery scenarios + the 4th no-data scenario lands as source=\'skipped_no_data\' with no broadcast.

usgs_nwis deferred to v0.5.12 (threshold-curation work). Master OFF in prod.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

meshai/persistence/db.py

@@ -30,7 +30,7 @@ logger = logging.getLogger(__name__)
 
 DEFAULT_DB_PATH = "/data/meshai.sqlite"
 MESHAI_DB_PATH_ENV = "MESHAI_DB_PATH"
-SCHEMA_VERSION = 2
+SCHEMA_VERSION = 3
 SCHEMA_META_TABLE = "schema_meta"
 MIGRATIONS_DIR = Path(__file__).parent / "migrations"