Fix five ports' docs builds and tidy the port landing page - #296

scripts/lib/core-trace.mjs:151:9: Prefer String#startsWith over a regex with a caret.

scripts/lib/workspace-showcase-sources.mjs:161:79: Parameter 'refuses' is declared but never used. Unused parameters should start with a '_'.

scripts/gen-registry.mjs:194:24: Prefer String#endsWith over a regex with a dollar sign.

scripts/lib/core-recipes/powershell.mjs:2:10: Identifier 'chmodSync' is imported but never used.

scripts/lib/core-recipes/julia.mjs:63:51: Unnecessary escape character '$'

scripts/lib/core-recipes/julia.mjs:63:44: Unnecessary escape character '$'

scripts/lib/core-recipes/julia.mjs:63:15: Unnecessary escape character '$'

scripts/lib/core-recipes/ts.mjs:32:7: Variable 'handle' is declared but never used. Unused variables should start with a '_'.

scripts/lib/core-recipes/ruby.mjs:121:74: Prefer String#startsWith over a regex with a caret.

scripts/gen-mcp-protocol.mjs:173:31: Unsafe `finally` block.