✨ Emit precompressed sidecars for served assets

Add scripts/precompress.ts, a dependency-free Node 26 tool that writes
.br/.gz/.zst sidecars next to every text asset and keeps the originals, so
static-web-server can serve the variant matching Accept-Encoding and fall
back to the original. The coverage publish step runs it on the copied report.

Wire scripts/*.ts into the toolchain: type-check (tsconfig include), lint and
fix (oxlint paths), knip entry (CI invokes the file rather than importing it),
and a narrow .oxlintrc override allowing node:* imports in Node CLI scripts.

package.json

@@ -42,12 +42,12 @@
         "check": "npm run check:tsc && npm run check:oxlint && npm run check:oxfmt && npm run check:cspell",
         "check:cspell": "cspell lint ${LEFTHOOK_FILES:-.}",
         "check:oxfmt": "oxfmt --check ${LEFTHOOK_FILES:-.}",
-        "check:oxlint": "oxlint ${LEFTHOOK_FILES:-src}",
+        "check:oxlint": "oxlint ${LEFTHOOK_FILES:-src scripts}",
         "check:tsc": "tsc",
         "clean": "rm -rf dist coverage",
         "fix": "npm run fix:oxlint && npm run fix:oxfmt",
         "fix:oxfmt": "oxfmt ${LEFTHOOK_FILES:-.}",
-        "fix:oxlint": "oxlint --fix src",
+        "fix:oxlint": "oxlint --fix src scripts",
         "create:branch": "./scripts/branch.sh",
         "create:release": "./scripts/release.sh",
         "maintain": "npm run maintain:knip; npm run maintain:outdated",