refactor(pdf): increase tax watermark spacing ## Changes The RAHASIA watermark on SKPD documents is too crowded. Increase the shared pattern's horizontal spacing from 124 to 160 points and vertical spacing from 64 to 88 points, reducing stamp density by about 44% across tax PDFs. The existing font, letter spacing, stamp size, and opacity are preserved. Closes #1743. ## Release impact Patch. Improve the layout of the existing tax-document watermark. ## Migration notes No migration or configuration changes are required. The spacing applies to newly generated PDFs. ## Validation - All nine focused lock regressions passed after merging the latest production branch. - Runner routing and JavaScript syntax checks passed. - The resolved build workflow, lock tests, and CI documentation exactly match production. The final PR diff changes only the two watermark spacing constants. - `git diff --check` passed. - No local application build or dev server was run.