enhance(#3626): make CONTEXT.md seam claims checkable via a SEAM.*.enforced-by gate (#3975)

* feat(#3626): make CONTEXT.md seam claims checkable via SEAM.*.enforced-by gate

Adds SEAM.<id>.owns / SEAM.<id>.enforced-by=lint-rule:<name>|test:<path>
predicates to CONTEXT.md, generalizing the existing WORKTREE.SEAM.* shape,
plus scripts/lint-seam-enforcement.cjs (wired into lint:ci) which fails
when a declared single-owner seam names no existing, registered
enforcement mechanism. Backs all six current module-level single-seam/
single-canonical-owner claims found in CONTEXT.md, including the Shell
Command Projection Module's Windows-binary-resolution claim via #3619's
local/no-private-binary-resolution rule.

Scope is resolves-only per maintainer decision: the gate proves an
enforcement pointer exists and is registered, not that its surface
covers every file the seam claims. See docs/adr/3626-context-md-seam-claim-gate.md.

Closes #3626

* fix(#3626): back the Package Identity Module's seam claim too

Isolated adversarial review caught a miss in the "no grandfather list"
sweep: the Package Identity Module also declares itself "Single seam
owning GSD's published-package coordinates" and already names its real
enforcement (scripts/lint-package-identity-drift.cjs). Backs it with
SEAM.package-identity.owns/enforced-by=test:tests/package-identity.test.cjs,
bringing the total to 7 backed seams. Also makes explicit, in the design
doc and ADR, that function-level "single owner" sentences inside
already-covered modules (STATE.md Document Module, etc.) are deliberately
out of scope — a seam claim is about a module's boundary, not every
function inside it.

* docs(#3626): backfill changeset PR number

---------

Co-authored-by: sim <sim@local>

package.json

@@ -121,7 +121,7 @@
     "lint:table-schema-drift": "node scripts/lint-table-schema-drift.cjs",
     "lint:frontmatter-scalar-broad-grep": "node scripts/lint-frontmatter-scalar-broad-grep.cjs",
     "lint:removed-but-needed": "node scripts/lint-removed-but-needed.cjs",
-    "lint:ci": "npm run lint && npm run lint:skill-deps && npm run lint:generated-sync && node scripts/lint-test-file-count.cjs && node scripts/lint-command-contract.cjs && node scripts/lint-pr-check-project-dir.cjs && npm run lint:legacy-name && node scripts/lint-regression-test-names.cjs && node scripts/lint-allow-test-rule-refs.cjs && node scripts/lint-resolution-provenance.cjs && node scripts/lint-portable-timeout.cjs && node scripts/validate-registry.cjs && node scripts/lint-table-schema-drift.cjs && node scripts/lint-fix-has-regression-tests.cjs && node scripts/lint-example-parser-parity.cjs && node scripts/lint-docs-command-form.cjs && node scripts/lint-plan-count-drift.cjs && node scripts/lint-milestone-window-drift.cjs && node scripts/lint-phase-enumeration-drift.cjs && node scripts/lint-planning-prompt-drift.cjs && node scripts/lint-unreachable-guard-drift.cjs && node scripts/lint-completion-ratio-drift.cjs && node scripts/lint-state-field-drift.cjs && node scripts/lint-state-write-path-drift.cjs && node scripts/lint-completion-predicate-drift.cjs && node scripts/lint-planning-snapshot-bypass-drift.cjs && node scripts/lint-health-diagnostic-rule-table.cjs && node scripts/lint-planning-artifact-writer-drift.cjs && node scripts/lint-frontmatter-scalar-broad-grep.cjs && node scripts/lint-removed-but-needed.cjs && node scripts/lint-no-adhoc-regex-escape.cjs && node scripts/lint-vendored-deps.cjs && node scripts/lint-docs-guard-registration.cjs && node scripts/lint-source-test-name-collision.cjs && npm run lint:hooks-runtime-build-seam && node scripts/check-contract-drift.cjs && node scripts/lint-mutation-test-derivation-drift.cjs",
+    "lint:ci": "npm run lint && npm run lint:skill-deps && npm run lint:generated-sync && node scripts/lint-test-file-count.cjs && node scripts/lint-command-contract.cjs && node scripts/lint-pr-check-project-dir.cjs && npm run lint:legacy-name && node scripts/lint-regression-test-names.cjs && node scripts/lint-allow-test-rule-refs.cjs && node scripts/lint-resolution-provenance.cjs && node scripts/lint-portable-timeout.cjs && node scripts/validate-registry.cjs && node scripts/lint-table-schema-drift.cjs && node scripts/lint-fix-has-regression-tests.cjs && node scripts/lint-example-parser-parity.cjs && node scripts/lint-docs-command-form.cjs && node scripts/lint-plan-count-drift.cjs && node scripts/lint-milestone-window-drift.cjs && node scripts/lint-phase-enumeration-drift.cjs && node scripts/lint-planning-prompt-drift.cjs && node scripts/lint-unreachable-guard-drift.cjs && node scripts/lint-completion-ratio-drift.cjs && node scripts/lint-state-field-drift.cjs && node scripts/lint-state-write-path-drift.cjs && node scripts/lint-completion-predicate-drift.cjs && node scripts/lint-planning-snapshot-bypass-drift.cjs && node scripts/lint-health-diagnostic-rule-table.cjs && node scripts/lint-planning-artifact-writer-drift.cjs && node scripts/lint-frontmatter-scalar-broad-grep.cjs && node scripts/lint-removed-but-needed.cjs && node scripts/lint-no-adhoc-regex-escape.cjs && node scripts/lint-vendored-deps.cjs && node scripts/lint-docs-guard-registration.cjs && node scripts/lint-source-test-name-collision.cjs && npm run lint:hooks-runtime-build-seam && node scripts/check-contract-drift.cjs && node scripts/lint-mutation-test-derivation-drift.cjs && node scripts/lint-seam-enforcement.cjs",
     "lint:allow-test-rule-refs": "node scripts/lint-allow-test-rule-refs.cjs",
     "lint:regression-names": "node scripts/lint-regression-test-names.cjs",
     "lint:descriptions": "node scripts/lint-descriptions.cjs",
@@ -133,6 +133,7 @@
     "lint:docs": "node scripts/lint-docs-required.cjs",
     "lint:qa-smells": "node scripts/qa-smell-ratchet.cjs",
     "lint:legacy-name": "node scripts/lint-legacy-dir-name.cjs",
+    "lint:seam-enforcement": "node scripts/lint-seam-enforcement.cjs",
     "lint:docs-command-form": "node scripts/lint-docs-command-form.cjs",
     "lint:hooks-runtime-build-seam": "node scripts/lint-hooks-runtime-build-seam.cjs",
     "ci:test-scope": "node scripts/ci-test-scope.cjs",