Remove misclassified cncmill1-context entries from linuxcnc/memory/

Operator caught two leaks that my Phase 4c grep missed: both files were
classified as 'linuxcnc fork knowledge' in Phase 1, but their content
is heavily cncmill1 work, not anything about the linuxcnc fork itself.
The straddle rule should have applied — cncmill1 work that uses the
fork stays in lab/cncmill1/memory/, not linuxcnc/memory/.

Removed:
- memory/reference_runtime_latest.md
  Leaked content: 'auto-discovers linuxcnc repo as sibling of lab repo
  root', src/linuxcnc/screens/qtdragon_hd/{release,latest}/ paths
  (cncmill1/src structure, not anything in the linuxcnc fork). The
  RUNTIME=latest mechanism is implemented in cncmill1's Makefile, not
  in this fork.

- memory/reference_test_timings.md
  Leaked content: spindle-slip-fix reference, base/logic/ui/panels
  test suite (cncmill1's pyramid, not the linuxcnc fork's runtests),
  panel phases (spindle/tuning/zcal/lube — cncmill1 subsystems),
  panel button labels (Move-to-Safety, Apply, Test Gains —
  cncmill1 panel widgets), test_helpers.sh check_atspi_health
  (cncmill1's test framework). None of this describes the linuxcnc
  fork itself.

Both files are being added to lab/cncmill1/memory/ in a follow-up
commit on the lab repo, where they belong per the straddle rule.

The deletions are an overlay commit on the public fork — both files
were briefly visible on the session branch since Phase 4c
(commit 8b46870), and the commit history preserves them. The
public fork policy is no force-push, so the past visibility cannot
be undone, only overlaid. The leaked content is not catastrophic
(no credentials, no PII) but is private project context that
shouldn't have been pushed.

Lesson: the public-fork grep pattern needs to catch contextual
project terms (spindle-slip, M3/M4, panel phase names, run-dev-sim,
INI parameter names, test_helpers.sh) in addition to literal path
strings (cncmill1, lab/, ~/is-dev). Grep alone isn't enough — needs
human review of every file going to the public fork, even files
that pass the path-string grep.

Author: igor

MEMORY.md

@@ -2,8 +2,6 @@
 
 - [Fork one-time setup](memory/reference_fork_setup.md) — 8-step setup procedure for a fresh clone (Debian, debian/control, build/runtime deps, configure, agent-helpers hooks, setuid, RT tuning)
 - [halcompile workflow](memory/reference_halcompile_workflow.md) — compile-and-symlink pattern for sudo-once unattended `.comp` recompiles, halcompile naming gotcha, `variable` keyword usage
-- [RUNTIME=latest workflow](memory/reference_runtime_latest.md) — default is the locally-built fork; `release` keyword switches to system-installed; rip-environment auto-source semantics
-- [Test timings](memory/reference_test_timings.md) — healthy sim suite baselines; if panel tests exceed 150s suspect AT-SPI hang
 - [Upstream PR workflow](memory/reference_upstream_pr_workflow.md) — full procedure for `agent-helpers/upstream-pr-prep.sh`, prerequisites, worktree rationale, build-flag CI parity, worked example PR #3933
 - [Teleop velocity leak](memory/reference_teleop_velocity_bug.md) — upstream `axis_sync_teleop_tp_to_carte_pos` doesn't reset `curr_vel`/`curr_acc`; post-homing drift; fork master commit `f40e8e64bc`, upstream PR #3933
 - [Public fork hygiene](memory/feedback_public_fork.md) — never reference private repo names, paths, or links from any committed file in this fork