feat(interest): add public interest tracking for members of Congress

Adds Google Trends, NewsAPI, and Google News RSS scoring for members,
mirroring the existing bill interest pipeline. Member profiles now show
a Public Interest chart (with signal breakdown) and a Related News panel.

Key changes:
- New member_trend_scores + member_news_articles tables (migration 0008)
- fetch_gnews_articles() added to news_service for unlimited RSS article storage
- Bill news fetcher now combines NewsAPI + Google News RSS (more coverage)
- New member_interest Celery worker with scheduled news + trend tasks
- GET /members/{id}/trend and /news API endpoints
- TrendChart redesigned with signal breakdown badges and bar+line combo chart
- NewsPanel accepts generic article shape (bills and members)

Co-Authored-By: Jack Levy

backend/alembic/versions/0008_add_member_interest_tables.py

@@ -0,0 +1,54 @@
+"""add member trend scores and news articles tables
+
+Revision ID: 0008
+Revises: 0007
+Create Date: 2026-03-01
+"""
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0008"
+down_revision = "0007"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table(
+        "member_trend_scores",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("member_id", sa.String(), nullable=False),
+        sa.Column("score_date", sa.Date(), nullable=False),
+        sa.Column("newsapi_count", sa.Integer(), nullable=True, default=0),
+        sa.Column("gnews_count", sa.Integer(), nullable=True, default=0),
+        sa.Column("gtrends_score", sa.Float(), nullable=True, default=0.0),
+        sa.Column("composite_score", sa.Float(), nullable=True, default=0.0),
+        sa.ForeignKeyConstraint(["member_id"], ["members.bioguide_id"], ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("member_id", "score_date", name="uq_member_trend_scores_member_date"),
+    )
+    op.create_index("ix_member_trend_scores_member_id", "member_trend_scores", ["member_id"])
+    op.create_index("ix_member_trend_scores_score_date", "member_trend_scores", ["score_date"])
+    op.create_index("ix_member_trend_scores_composite", "member_trend_scores", ["composite_score"])
+
+    op.create_table(
+        "member_news_articles",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("member_id", sa.String(), nullable=False),
+        sa.Column("source", sa.String(200), nullable=True),
+        sa.Column("headline", sa.Text(), nullable=True),
+        sa.Column("url", sa.String(), nullable=True),
+        sa.Column("published_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("relevance_score", sa.Float(), nullable=True, default=0.0),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.ForeignKeyConstraint(["member_id"], ["members.bioguide_id"], ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("member_id", "url", name="uq_member_news_member_url"),
+    )
+    op.create_index("ix_member_news_articles_member_id", "member_news_articles", ["member_id"])
+    op.create_index("ix_member_news_articles_published_at", "member_news_articles", ["published_at"])
+
+
+def downgrade():
+    op.drop_table("member_news_articles")
+    op.drop_table("member_trend_scores")