Add search with match highlighting

[mcollina]

Closes #24

What

Adds frame search to FullFlameGraph and the CLI-generated HTML:

• New SearchControls component: a search input with prev/next navigation, match counter, and keyboard support (Enter / Shift+Enter cycle through matches, Escape clears).
• Matching is a case-insensitive substring test against function name and file name; matches are ordered hottest-first.
• All matching frames are highlighted live in the flame graph: matches render at full opacity while non-matching frames (and their labels) are dimmed. Clearing the query restores normal rendering.
• Selecting a match drives the existing selection machinery, so it zooms to the frame and opens Stack Details.

How

• FrameRenderer accepts an optional set of highlighted frame IDs and computes per-frame opacity from it; text labels reuse the same opacity map.
• FlameGraphRenderer exposes setHighlightedFrames(frameIds | null), which re-renders immediately without triggering zoom animations.
• FlameGraph gets a highlightedFrameIds prop, re-applied when the renderer is recreated (e.g. toggling "Show App Code Only" mid-search).
• FullFlameGraph gets a showSearch prop (default true) and wires SearchControls matches into FlameGraph.
• Exported from the package root; component docs and Storybook stories included, matching existing conventions.

Bug fixes

Search is the first feature to read frame names from FullFlameGraph's internal frame list, and it exposed two pre-existing bugs there:

• Frame names were resolved via profile.stringTable[i] instead of profile.stringTable.strings[i], so every frame was named func_N. Fixed, and file name / line number are now extracted too.
• Node IDs were missing the root/ prefix used by the renderer and frameMap, so selections resolved to nothing (zeroed values in Stack Details, no sync with hottest-frames navigation).

Testing

• New tests/search-controls.spec.ts (9 tests): rendering, match counting, file-name matching, match cycling, Escape behavior, and a canvas-level check that searching actually changes the rendering and clearing restores it.
• Full Chromium suite passes: 224/224.
• Verified interactively in CLI-generated HTML (search, highlight, cycle, clear).

[leorossi]

LGTM