Catch CHANGELOG.md up to the many features shipped since 0.9.0

[Jagadeeshftw]

📌 Description

CHANGELOG.md's most recent entry is [0.9.0], covering aria-sort on sortable headers. Since then, the codebase has clearly shipped a substantial number of additional features that aren't reflected anywhere in the changelog — among them: dark/light theme support (ThemeProvider, lib/theme.ts), URL querystring sync for filters/search (useQueryState), debounced search (useDebouncedValue), CSV export for settlements, breadcrumbs on detail pages (Breadcrumb), a skip-to-content link (SkipToContentLink), a global unhandled-rejection reporter (GlobalErrorHandler, lib/errorReporter.ts), and request retry/backoff in lib/api.ts. package.json's version is still 0.9.0, so the changelog is not merely behind a version bump — it's missing real, shipped functionality.

🧩 Requirements and context

• Add changelog entries for the notable features shipped since the [0.9.0] entry, grouped sensibly (e.g. a new [0.10.0] or [Unreleased] section per the file's existing ### Added/### Testing convention).
• Keep entries terse and consistent with the existing changelog's voice (see the [0.7.0]/[0.8.0] entries for the expected level of detail).
• Do not rewrite or reorganize the existing historical entries — only add what's missing.

🛠️ Suggested execution

• Diff the current src/ tree against what's already documented in CHANGELOG.md to compile the list of undocumented features (the description above is a starting point, not necessarily exhaustive).
• Add the new section(s) to CHANGELOG.md following its existing ## [x.y.z] / ### Added / ### Testing structure.
• Cross-check with package.json's version field and bump it if the maintainers' convention expects the changelog and version to move together (flag this as a question in the PR if unclear).

✅ Acceptance criteria

• CHANGELOG.md includes entries for the major features shipped after the [0.9.0] entry.
• New entries follow the file's existing formatting conventions.
• No existing historical entries are altered.

🔒 Security notes

Documentation-only; no runtime impact.

📋 Guidelines

• Minimum 95% test coverage
• Clear documentation
• Timeframe: 96 hours

[Jagadeeshftw]

Assigned. Please reference this issue in your PR (e.g. Closes #235) when it's ready. Contributor chat here: https://t.me/+vTbe0hOUKrFhNTJl