Add general Haskell skill with conditional relude guidance

[srid]

General-purpose Haskell skill covering error handling, type safety, idiomatic patterns, and code quality — the language-level guidance that complements the existing nix-haskell build skill.

The skill is split into two files: SKILL.md for universal Haskell best practices (total functions, Text over String, newtype wrappers, Aeson via generic deriving, HLint compliance), and a companion RELUDE.md that the agent loads only when the project actually uses relude. This keeps the base skill prelude-agnostic while giving relude-heavy projects the idiomatic substitutions they need (pass, ordNub, whenJust, typed IO helpers, etc.).

Build workflow guidance (ghcid) is kept conditional — "if ghcid.txt exists, check it" — rather than mandating a specific toolchain.

Closes #27

[srid]

Execute Results

Step	Status	Duration	Verification
sync	✓	0s	git fetch ran without error
research	✓	39s	Fetched issue #27, reference files, AGENTS.md
hickey	✓	41s	Structurally simple, ghcid made conditional
branch	✓	39s	Draft PR #28 created
implement	✓	53s	SKILL.md, RELUDE.md, README.md
docs	✓	15s	README table updated
police	✓	74s	3 issues found and fixed
fmt	✓	32s	No format command (skipped)
commit	✓	20s	97ff187 pushed
test	✓	0s	No tests (skipped)
ci	✓	21s	No CI (skipped)
update-pr	✓	14s	Scope verified, marked ready
Total		5m 48s

Workflow completed at 2026-04-04T14:01:59Z.