Remove Yml's repository PR templates #9

Context and request

PR authors use the canonical MSX PR-format guidance instead of a repository PR-template file. This is Yml's independently reviewable delivery leaf for campaign no-pr-template-files, following the user decision to remove local and central defaults rather than rely on GitHub fallback.

Acceptance criteria

• Yml contains no tracked automatic single-file or multiple-choice GitHub PR templates in any supported location or case variant.
• CONTRIBUTING.md retains its resolving canonical PR-format link, with no replacement template or central-fallback instruction.
• The diff changes only actual PR-template files and any directly dependent links if needed; module code, contribution guidance, issue forms, and unrelated files remain intact.
• One small commit is delivered in a separate draft PR targeting main; no merge, auto-merge, release, prerelease, tag, label, permission, or workflow-rule mutation is performed.

Technical decisions

The verified source is default-branch commit 93d2656563a719d99416b9e13a05e65f6f815498; its sole tracked PR template is .github/pull_request_template.md, blob ff2067e739e6d90bfa95905df89fa752cccd2e83. Delete that file without replacement. Inspect all tracked case-insensitive pull_request_template filenames and directories before and after deletion, so other real variants cannot be missed. Existing contribution guidance already points to the canonical PR-format page and does not depend on the deleted path.

Use tracked-file absence assertions, exact-diff checks, and an HTTP/content check of the retained canonical guidance. Module tests are not applicable to this deletion-only change. Do not run publishers, dispatch workflows, or trigger a real prerelease. The unchanged caller uses Process-PSModule v6.1.16 at 1653be8d36607d9535f600278c44789979477813; its default important-file patterns are ^src/ and ^README\.md$, so this deletion does not enable build, test, module publication, or site publication on an opened/synchronized PR. Draft status alone is not the publication guard.

The final canonical evidence is frozen at MSXOrg/docs commit bc03a5992615f65d1d5346dc48e7506e80b8b6ca: Repository Standard: No PR-template files owns the prohibition, while PR Format: Complete description example owns the actual record, not a distributed scaffold. MSXOrg/docs#209 is ready but unmerged at that head. MSXOrg/.github#8 and PSModule/.github#82 remain separately owned, unmerged drafts. These immutable sources are evidence, not a claim that the policy or defaults are integrated. Preserve exact-head CI, source-integration, and publication-safety gates; keep the delivery draft and do not assume canonical release-label support in the unchanged legacy v6.1.16 producer. Do not absorb this work into the unrelated dependency update PSModule/Yml#8, upgrade the framework, or change labels, permissions, validators, or workflow policy in this PR.

Implementation plan

• Verify the baseline template inventory and blob, search native delivery candidates, and inspect the caller's exact publication gates before implementation.
• Delete the actual tracked PR template without replacement and update only a directly dependent link if one exists.
• Verify zero remaining automatic template variants, the exact deletion-only diff, and the resolving retained canonical-format guidance; commit the focused removal.
• Open a main-targeting draft without release or label mutations, record campaign identity and evidence, and report live checks and remaining source-contract blockers.