Enrich the query/transform algebra (rule composition, ellipsis, templates, strategies)

[konard]

Context

Issue #47's title demands "the richest features set" against all competitors.
The code-tooling survey (competitors-code-tooling.md)
identifies query/transform operators that competitors ship and meta-language
lacks. LinkQuery covers type/term/language/named/S-expressions/captures;
ReplacementRule/SubstitutionRule cover replace-and-substitute. See
requirements.md R-11 (extension) and
solution-plans.md S-12.

Scope

Operators to add over links (each with competitor provenance):

• Relational, composable rule algebra: inside, has, precedes,
  follows, all/any/not, named reusable sub-rules (ast-grep).
• Ellipsis (...) gap matching and kind-constrained (typed) metavariables
  (Semgrep, Coccinelle).
• Grammar-less fallback matching over plain-text token links for unwired
  languages (Comby).
• Quasiquote replacement templates with placeholder safety and
  parenthesization-conservative reprinting (Babel template, Recast).
• Traversal-strategy combinators: topdown, bottomup, innermost,
  fixpoint (Stratego, Rascal).
• A valid/invalid snapshot test harness for rules (ast-grep) so rule suites
  are self-verifying.

Acceptance criteria

• Each operator has unit tests plus at least one parity fixture ported
  from the competitor that motivated it.
• S-expression syntax extended (or a documented alternative added) so the
  new operators are reachable from text queries, not just builders.
• Existing query/transform tests pass unchanged.
• Changelog fragment added (bump: minor).

References

• Requirement: requirements.md R-11 (extension), issue title
• Solution: solution-plans.md S-12
• Part of We need to carefully compare all competitors in all scopes with out project, and make sure we have the richest features set #47; work lands on branch issue-47-76af108c0f24 (PR Finish issue #47 parity feature set #48).

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Filed from docs/case-studies/issue-47/proposed-issues/12-query-transform-algebra.md. Part of the implementation plan for #47.