Cross-platform support: platform-aware update pipeline, POSIX updater ops, and native macOS app build

[jucardi]

Summary

This PR makes the repository cross-platform-capable and adds a native macOS app build path.

Companion PR: the native macOS host (SimpleGraphic build + launcher) that make macos-app consumes is PathOfBuildingCommunity/PathOfBuilding-SimpleGraphic#111.

It has two logical parts:

1. Cross-platform readiness (standalone, fully backward-compatible):

• update_manifest.py / manifest.cfg: platform tagging is now config-driven (part/platform section options) instead of hardcoding win32, so future per-platform runtime bundles need no client changes. Extensionless files (POSIX executables) are no longer skipped by the glob. manifest.xml regenerated (attribute change runtime="win32" → platform="win32"; per-file platform tags on runtime files).
• UpdateApply.lua: the infinite destination-open retry loop (which spins forever on a POSIX permission error) is now bounded with a clear error; new chmod op preserves executable bits; source handle closed on the error path.
• UpdateCheck.lua: emits chmod ops for extensionless runtime files on non-win32 platforms. Win32 op output is byte-identical (spec-pinned).
• GetCloudProvider and jit.opt are now optional host APIs (alternate hosts like pobfrontend don't provide them).
• New spec enforces case-sensitive Assets/ references (a recurring Linux bug class — it immediately caught and fixed two Assets/breachicon.png → BreachIcon.png mismatches).
• First test coverage for the update pipeline: an end-to-end UpdateCheck harness with a fake curl, UpdateApply op-interpreter specs, and pytest coverage for the manifest generator.

Backward compatibility: deployed win32 clients are unaffected. They include a remote <File> iff it has no platform attribute or it matches their local platform; adding platform="win32" to runtime files keeps them selected exactly as before. Verified against the deployed client logic in review.

2. Native macOS app build (arm64):

• New root Makefile: test (Docker busted suite), test-python, manifest, macos-runtime, macos-app, run-macos, clean-macos.
• make macos-app assembles build/macos/Path of Building.app from a sibling build of SimpleGraphic: flat Contents/MacOS/ bundle mirroring the Windows runtime/ layout, pob: URL scheme, ad-hoc codesign.
• The app is a dev-mode thin shim over the checkout (runs src/Launch.lua; user data stays in src/). Auto-update is deliberately disabled: the published manifest has no macOS runtime section yet, and an update-enabled macOS install would delete its own native runtime. Updater parity is follow-up work (see docs/crossPlatform.md).
• Docs: docs/crossPlatform.md (platform model + host contract) and a CONTRIBUTING macOS build section; also fixes a stale -PoE2.exe filename in CONTRIBUTING.

Dependency note: make macos-app requires the macOS build of SimpleGraphic, submitted as PathOfBuildingCommunity/PathOfBuilding-SimpleGraphic#111 (until it merges, the branch is available at jucardi/PathOfBuilding-SimpleGraphic feat/macos-build). Everything in part 1 is independent of it.

Testing

• Full busted suite: 472/472 (baseline 463 + 9 new spec cases), run in the repo's Linux CI container.
• New tests/test_update_manifest.py: 2/2. (tests/test_fix_ascendancy_positions.py has 2 pre-existing failures on dev, untouched here.)
• macOS app verified end-to-end: renderer init ~160 ms, full startup ~2.2 s, tree/uniques/rares loaded, open-launch, settings persist to the checkout on quit, pob:// links launch the app (URL delivery to a running instance is a documented limitation).

Known limitations (documented in CONTRIBUTING)

• macOS: pob:// Apple-Event delivery is launch-only/best-effort; the app writes imgui.ini/logs inside its bundle (discarded on rebuild; build data unaffected).
• Accepted tradeoff: the bounded updater retry fails visibly on a persistent Windows file lock instead of hanging forever (staged files are reused on the next attempt).

🤖 Generated with Claude Code