fix: apply number format options to zero ticks

[pentaoa]

Fixes #11905. Revisits the zero-tick formatting problem from the author-closed #12260.

Numeric ticks return the literal 0 before applying ticks.format, so currency and percent axes lose their unit at zero. Format zero with the configured locale/options, using zero fractional digits by default and allowing explicit precision to override that default. Keep zero outside automatic scientific-notation selection.

Added chart-level regressions for percent, currency, and explicit two-decimal currency formatting, plus coverage for the existing plain-zero behavior with empty, single-tick, fractional, and large-range tick lists.

Validation on macOS arm64, Chrome Headless 151:

• The new formatting regression fails on the original code (0 instead of 0%, $0, and $0.00); all 6 core.ticks tests pass with the fix.
• pnpm run lint passes, including the build and type checks (existing warnings in unchanged files).
• Full Karma suite: 1,697 passed, 7 failed. Unmodified master: 1,695 passed, the same 7 image-diff failures. The failures are in filler, radialLinear, time, and timeseries image fixtures; no new failures.
• Rendered currency and percent charts and inspected the resulting labels visually.

AI assistance: OpenAI Codex assisted with implementation, tests, and verification.