Add inherited defaults for hiding leading metadata rows

[jonaraphael]

Users opening many CSV files with the same metadata preamble currently have to set Hide First N Rows for every file. This adds the resource-scoped csv.defaultIgnoreRows integer setting (default 0), so global, workspace and folder defaults apply when a file has no override.

Per-file values take precedence, including an explicit 0 to show all rows. Leave the existing CSV: Hide First N Rows input blank to clear its override and inherit again. Hidden metadata remains in the document and saved file. README and the setting contribution are synchronized; no additional command is introduced.

Default changes refresh only affected files that inherit the setting. A visible editor commits its current edit, persists view state and acknowledges readiness before the host's ordered queue rebuilds the view, preserving a live multiline draft. This safe refresh path also handles the per-file command.

Addresses #99. Stacked on #117 to validate inherited metadata defaults together with frozen panes; includes the shared stacked-PR CI correction.

Validation:

• Node 20.20.0, npm ci, npm run compile, npm test: all 192 tests pass, including five new regressions.
• Tests cover resource-specific configuration lookup, explicit 0 versus absent override, positive overrides, blank reset, cancellation, workspace default changes, avoiding refresh for explicit overrides, metadata preservation, frozen-row source identities and commit-before-refresh of an active multiline draft.
• npm run lint: zero errors, same 87 existing warnings. git diff --check passes.
• Native settings UI smoke/screenshots remain for review; automated checks execute the actual command handlers, provider messages and jsdom webview.

Independent orchestrator review: inspected override inheritance and the ordered edit-commit/refresh handshake. Compile, lint and all 192 tests passed with the updated frozen-pane/high-contrast stack.

Cross-feature integration: the current combined release candidate passes compile, lint (0 errors; 86 existing warnings) and 571 tests. This branch includes #117’s divider-color fill on every frozen-row seam and its screenshot; measured row spacing, hidden metadata and unfreeze cleanup remain covered.

Palette-stack verification: inherited the narrowed #114 without changing this PR's feature logic. Compile, full tests and lint pass on the current head; the browser confirms high-contrast frozen selection/find states retain datatype colors, and theme transitions preserve live/queued edits in the combined candidate. Combined verification head: 2f43410.

Frozen-row regression verification: includes #117's opaque divider paint for every pinned row, including serial/corner cells. The paint changes no row geometry, datatype colors, selection/Find surfaces or editing handlers. Chromium checks cover all four themes and filtered source rows with hidden metadata, no header and 110% zoom. The combined 2f43410 build passes compile and 571 tests.