patch: full table vocabulary + patch_view / patch_dictionary

[orian]

Summary

Implements #154 — all five asks. After #153, 70 objects in posthog-cloud-infra were still copied per env, each blocked on a field no patch could carry (~30 on engine alone). The patch vocabulary is now complete:

patch_table carries the full delta:

patch_table "raw_sessions" {
  engine "distributed" { cluster_name = "posthog", ... }  # replace wholesale
  order_by     = [...]                                    # replace when set
  ttl          = "..."                                    # replace when set
  column "x" { ... }                                      # add
  modify_column "y" { ... }                               # in-place replace
  drop_columns = ["z"]
  index "i" { ... }                                       # add
  drop_indexes = ["j"]                                    # drop first → drop+add redefines
  settings = { ... }                                      # merge, patch wins (as before)
}

• Column order within a patch: modify → drop → add (an add sees the post-drop state; modify_column keeps position).
• engine replaces wholesale — per the issue, merging engine sub-arguments is not meaningful. The Distributed-target-moves-with-topology case is now one engine block per env instead of a 20-line copy.
• Still non-patchable by design: primary_key, comment, constraints, projections — a table differing there is genuinely different, which is override = true's job.

patch_view (query, comment) and patch_dictionary (source/layout/lifetime replace wholesale, settings merge) give the last two object kinds a patch form. Unknown targets error, like patch_table.

Correctness details:

• Patched values canonicalize exactly like declared ones (column/index expressions, patch_view queries through normalizeQuery, engine + dictionary source/layout decoded at parse) — a patched object converges with its introspected form (introspect is not round-trip-consistent with compose (sha-0409212): spurious diffs on unchanged view queries, MATERIALIZED columns, minmax indexes, and Distributed-proxy columns #136 discipline).
• The locate scanner records patch_view/patch_dictionary as patch sites, so -duplicates stays exempt-correct.
• Patches still accumulate in layer order and apply before extend.

Plan doc: docs/plans/2026-07-17-patch-vocabulary.md. Docs: reference (patch_table rewritten, new patch_view/patch_dictionary section, pipeline + decision table), FAQ (engine question now "yes", two new worked entries: Distributed-per-env and view/dictionary patching), README, CLAUDE.md.

Note: this branch is stacked on #155 (the extend/patch_table docs explainer) so both PRs edit the same doc sections without conflicts. Merge #155 first and this diff reduces to the vocabulary work — or merge this one and #155's content lands with it.

Test plan

• patch_vocabulary_test.go: the issue's raw_sessions engine scenario through LoadLayers + a cross-env diff that is exactly the engine change; scalar replace-when-set; column modify/drop/add ordering + all error paths; index drop+add redefine + errors; patch_view heredoc/one-liner convergence, comment replace, unknown target; patch_dictionary source/lifetime replace + settings merge + unknown target; locate exemption
• Repurposed TestParseFile_PatchDisallowedAttribute (engine is legal now; primary_key stands in for the still-rejected fields)
• go test -race ./internal/... ./cmd/... ./test — 985 passed; gofmt -s clean
• Smoke-tested the built binary: composed dev layer carries the patched engine + normalized patched query; diff -left cloud -right cloud,dev reports exactly the engine change and query change