refactor(installer): extract update marker region verbatim

[andrexibiza]

The Tauri bootstrap updater's update-marker region lives inside apps/bootstrap-installer/src-tauri/src/update.rs. This extraction moves it verbatim into its own module so the ownership/refusal logic has a stable seam for the coordinated update-ownership lanes.

Part of campaign #88683 and the installer sharding mandate #79922. Verbatim extraction, zero behavior change; the coordinated ownership work (#95719, #97299 and follow-up lanes) targets the extracted update/marker.rs seam instead of the flattened file.

What this is

• apps/bootstrap-installer/src-tauri/src/update/marker.rs: the RAII UpdateMarkerGuard, MarkerOwner liveness/ownership inspection, self-heal refusal logic, and pid_is_alive — moved byte-for-byte.
• apps/bootstrap-installer/src-tauri/src/update.rs: mod marker; declaration plus the region removed; no other line changes.

Verification

• Verbatim proof: all 182 deleted lines from update.rs reappear in marker.rs in the same order (script-verified line-by-line; zero missing lines); git diff --check passes.
• Cargo: cargo test in the standalone worktree — 27 passed, 0 failed (extraction receipt identical on the standalone head); module wiring compiles.

apps/bootstrap-installer/src-tauri/src/update.rs   | 183 +--------------------
apps/bootstrap-installer/src-tauri/src/update/marker.rs | 182 ++++++++++++++++++++
2 files changed, 183 insertions(+), 182 deletions(-)

Provenance

Single verbatim refactor commit authored as Axl Ibiza, MBA <andrexibiza@gmail.com>, pinned to current main c8cbc07030459162a85058a57f8155c4d9efcde0. No behavior, ownership, or refusal semantics change; the coordinated ownership improvements remain separate lanes that target this new seam.

[Enough1122]

AI code review — automated review for reference; please use your judgment.

PR #104379 — refactor(installer): extract update marker region verbatim

Summary: Moves the update-marker guard region out of update.rs into update/marker.rs via include!, with no logic change (the one visible delta is a tracing::warn! formatting normalization).

Findings (Non-blocking):

• include! is textual inclusion, so visibility, privacy, and drop-glue semantics are preserved by construction — lower risk than a mod extraction. I compared the moved region line-by-line against the removed block; they match.
• Future edits should go to marker.rs only; a brief comment at the include! site (or the existing module doc) already covers provenance. Nothing to change.

Verdict: Looks good. Clean verbatim extraction.