mcp(cli): packages/loopover-mcp missing loopover_clear_selftune_override (sibling loopover_get_selftune_override_audit already mirrored, #7997)

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⚠️ Definition of Done: this issue must be completed in full, in a single PR. Do not split this
work across multiple PRs, and do not defer any Deliverable below to a follow-up issue. A PR that
satisfies only some of the Deliverables, stubs a required test, or leaves a checkbox
partially-done does NOT resolve this issue and will be closed.

⚠️ Required pattern: mirror loopover_get_selftune_override_audit's registration in
packages/loopover-mcp/bin/loopover-mcp.ts (added by #7997 — "add remote + stdio + CLI surfaces for
the selftune override audit"), immediately above/below it in the same file, using apiDelete (already
used by the unwatch action) instead of apiGet.

Context

src/mcp/server.ts (the hosted remote MCP server) registers two selftune-override tools as a
read/write pair:

• loopover_get_selftune_override_audit — read the override audit trail
  (GET .../selftune/overrides/audit)
• loopover_clear_selftune_override — clear a repo's live self-tune override, requires
  confirm:true (DELETE .../selftune/overrides)

packages/loopover-mcp/bin/loopover-mcp.ts — the published local CLI/stdio MCP package — mirrors
most remote tools as local registerStdioTool wrappers over the same REST routes via apiGet/
apiPost/apiDelete helpers. #7997 added the CLI mirror for loopover_get_selftune_override_audit
(confirmed present at packages/loopover-mcp/bin/loopover-mcp.ts, both in the tool-catalog list and
in a registerStdioTool("loopover_get_selftune_override_audit", ...) block using apiGet). Its
write-side sibling, loopover_clear_selftune_override, has no entry anywhere in
packages/loopover-mcp/bin/loopover-mcp.ts — grep for clear_selftune/clearSelftune in that file
and in packages/loopover-mcp/CHANGELOG.md returns nothing. A CLI/stdio MCP user can read the
override audit trail but cannot clear an override without switching to the REST API directly.

Requirements

• Add loopover_clear_selftune_override to the CLI tool-catalog list in
  packages/loopover-mcp/bin/loopover-mcp.ts (the array entry with name/category/description,
  same block loopover_get_selftune_override_audit's catalog entry lives in), category
  "maintainer".
• Add a registerStdioTool("loopover_clear_selftune_override", ...) block, placed next to
  loopover_get_selftune_override_audit's block, using stdioToolDescription(...) for the
  description and an input shape matching the remote tool's (owner, repo, confirm: boolean).
• Handler: call apiDelete(${toolRepoBase(owner, repo)}/selftune/overrides, { confirm }) (the
  apiDelete helper already exists and is used by the unwatch action) and return the result via
  toolResult(...), matching the remote tool's confirm:true requirement — do not silently default
  confirm to true; an omitted/false confirm must be rejected the same way the remote tool
  rejects it.
• No OpenAPI/schema regeneration required: DELETE /v1/repos/:owner/:repo/selftune/overrides is an
  unchanged REST route — this issue only adds the CLI's local mirror of an MCP tool that already
  exists on the hosted server.

Deliverables

• loopover_clear_selftune_override added to the CLI tool catalog in
  packages/loopover-mcp/bin/loopover-mcp.ts.
• registerStdioTool("loopover_clear_selftune_override", ...) wired to apiDelete, requiring
  confirm:true the same way the remote tool does.
• Unit/integration test covering the happy path and the missing/false-confirm rejection path.

All deliverables are required in this one PR — there is no follow-up issue.

Test Coverage Requirements

99%+ Codecov patch target (codecov/patch, unsharded via npm run test:coverage) on every branch of
the new CLI tool registration, including the confirm-rejection branch. Add a regression test
asserting the CLI tool calls DELETE {repoBase}/selftune/overrides with the same query/body shape
the remote loopover_clear_selftune_override tool sends.

Expected Outcome

A loopover-mcp CLI/stdio user can clear a repo's live self-tune override the same way they can
already read its audit trail, closing the read/write asymmetry between the two CLI-mirrored
selftune-override tools.

Links & Resources

• src/mcp/server.ts: loopover_clear_selftune_override (the remote tool this issue mirrors
  locally), loopover_get_selftune_override_audit
• packages/loopover-mcp/bin/loopover-mcp.ts: loopover_get_selftune_override_audit's
  registerStdioTool block (the exact pattern to copy, swapping apiGet for apiDelete)
• feat(mcp): add remote + stdio + CLI surfaces for the selftune override audit #7997 — added the CLI mirror for loopover_get_selftune_override_audit

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JSO-6455