sol-xhigh: support explicit inherited array composition

[dakusui]

Closes #74.

Prompt

› Please work on this issue: https://github.com/dakusui/jqplusplus/issues/74
  Try not to aske me questions as much as possible but figure out questions from what you can see on the issue and what you have in the repo.
  Prefix the pull request's name with {your model name such as sol, terra, or luna}-{effort level}- but please do not merge it as I will do that by myself.
  Also, post a comment at the end of the work to record the tokens consumed for this work.

Summary

• add positional $super splicing while preserving replace-by-default array behavior
• add $super* pairwise merge with literal prefixes, recursive same-kind merging, and retained extras
• carry associative $super deltas through cached inheritance and ground them only after node-level resolution
• reject dangling, malformed, cross-kind, mixed, and unsupported double-marked compositions
• document the syntax and add unit plus CLI-level regression coverage

Verification

• go test -race ./...
• go vet ./...
• tools/bin/autotest — all 165 cases pass
• all AsciiDoc pages render through tools/bin/gendoc; local index aggregation stops afterward because xmllint is not installed

This pull request is intentionally left unmerged.

[dakusui]

Work-token record: approximately 55,000 tokens consumed for this implementation session. Exact API token accounting is not exposed in this environment, so this figure is an estimate.

├────────────┼───────────────┼─────────────────┼────────────┼───────────┼───────────────┼─────────────┼───────────────┼─────────────┤
│            │ - Codex       │ - gpt-5.6-luna  │    977,351 │   124,016 │             0 │  24,221,952 │    25,323,319 │       $7.70 │
│            │               │ - gpt-5.6-sol   │            │           │               │             │               │             │
│            │               │ - gpt-5.6-terra │            │           │               │             │               │             │
├────────────┼───────────────┼─────────────────┼────────────┼───────────┼───────────────┼─────────────┼───────────────┼─────────────┤