Consolidate native browsing and Search into one compact row

[debpalash]

Summary

• Replace stacked navigation and Search toolbars with one compact browsing row: destination picker, one editable query field, one Search submit action, Filters, Sort, and More.
• Keep the same row at compact widths using bounded controls and named tooltips; group Home, All content, Watching, and every source in the destination menu.
• Preserve contextual source searches, links, assistant and memory requests, Paste, Voice, Settings, history navigation, and playback access.
• Retain submitted queries for editing; cancel superseded memory lookups and make Clear cancel both search pipelines. Retained queries no longer prevent player chrome from hiding.
• Update GUI wiring regressions and existing source-navigation contracts. GUI drawing remains native DVUI code; these structural checks do not claim pixel verification.

Verification

• Native and headless builds pass.
• Zig unit tests: 2,454 passed.
• Feature suite: 482 passed, 0 failed, 0 warnings, 14 optional skips (496 registered).
• Web lifecycle tests: 55 passed.
• Isolated native zig build run launches, serves authenticated API status, and closes cleanly.
• Formatting and whitespace checks pass.

Native screenshot verification is pending because Screen Recording access is unavailable.