Extend visual system to search pages

[tripledoublev]

Summary

Stacked on #51. Extends the --maple-* token system into search result surfaces and shared components — the area explicitly kept out of scope in #51.

• New tokens: overlay backdrop color tokens added to bootstrap.scss
• Search result cards: gradient backgrounds, hover elevation (translateY + shadow), 2-col desktop / 1-col mobile layout
• TestimonyHit: full restyle — author/position/quote layout, 3-line description truncation
• ControlsBar pattern: unified search box + refinements bar across BillSearch, TestimonySearch, SearchPage
• RefinementPanel: FilterSection styling, formatted attribute labels, outline-secondary filter buttons
• ResultCount: larger font (0.95rem), semibold, color token
• Shared components: token cleanup in Footer, FollowingCard, HearingDetails, SubmitTestimonyForm, TestimonyPreview, ViewTestimony, HearingsScheduled, OverviewTab — spacing/shadow/color literals → --maple-*
• scripts/test-integration-ci.js: Firebase CLI path fix

Test plan

• Storybook smoke test: search result card components
• Manual sweep: /bills, /testimony, /hearings search pages
• Hover states on result cards (elevation + shadow)
• Filter panel open/close, button styling
• Result count label
• Mobile layout (1-col) vs desktop (2-col)
• No visual regressions on Footer, shared components