Cardano Updates

CHaP has a stale fetchgit hash for proto-lens (submodule content
changed upstream). Use the same workaround as cardano-node upstream:
fetch proto-lens ourselves with the correct hash, fix symlinks, and
pass via inputMap to override haskell.nix's internal fetchgit.

See: IntersectMBO/cardano-node nix/haskell.nix lines 22-41

The latest hydra HEAD has unresolvable deps (haskell-accumulator
needs librust_accumulator). Revert to the working pin. The proto-lens
sha256 mismatch in CHaP is an upstream issue — it affects hydra's
mingw/ucrt cross builds only.

The old haskell.nix had a stale sha256 for proto-lens's fetchgit
(which includes recursive submodules). Updating haskell.nix gets
the correct hash. Also removes the now-unnecessary sha256map entry
in hydraPkgs since the proto-lens hash is managed by haskell.nix
internals, not our sha256map.

The haskell.nix update pulled a newer nixpkgs-unstable that removed
ghc943 from the compiler set, breaking all evaluations.  Revert
haskell.nix to its previous pin while keeping CHaP at 2026-04-07
(needed for cardano-node 10.6.3/10.7.0).

CHaP index-state was 2026-02-09 but cardano-node 10.6.3 requires
2026-03-28. Update CHaP to 2026-04-07 and haskell.nix/hackage/stackage
to latest.

- cardano-node: 10.5.4 → 10.6.3 (latest stable, 2026-04-01)
- cardano-node-pre: add 10.7.0 pre-release as separate input/output
- cardano-cli: 10.3.0.0 → 10.15.1.0 (latest)

The 10.7.0 pre-release builds are output as cardano-tools-pre-* alongside
the stable cardano-tools-* builds.

The ogmios source-repository-package hash in kupo's sha256map was
stale, causing plan-to-nix to fail with a hash mismatch on all kupo
builds and the index job.

- Mithril: use cp -r + chmod -R u+w instead of --no-preserve=mode,
  which fails because directories are created read-only before children
  can be copied into them
- Pruned cardano-node: use inputMap instead of sha256map for
  ouroboros-consensus to avoid haskell.nix creating a fetchgit
  derivation whose name (URL + 40-char rev + 6 subdirs) exceeds
  the 207-character Nix store path limit

- Remove ogmiosPackages and encoinsPackages from build (GHC 8.10.7 no
  longer supported by haskell.nix)
- Disable hello-javascript (GHCJS linker bug with GHC 9.6.6)
- Fix libcxxabi overlay to fall back to libcxx on newer nixpkgs where
  libcxxabi was merged into libcxx
- Fix mithril Cargo.lock permission error by copying source with
  --no-preserve=mode before passing to crane