initial: inventory-list-display-test v0.1.0 — 9 assertions

Covers: create round-trip, non-container loud-error, action
register/unregister lifecycle, duplicate label + non-function
callback loud-errors, empty default action-set, contents ordering
via _test_get_rows, default icon-resolver property reads, custom
icon-resolver override via set_icon_resolver.

README.md

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+# lib-core.inventory-list-display-test
+
+Test module for `lib-core.inventory-list-display`. Runs 9 assertions
+headless via `engine.test.*` (TAP output).
+
+**Version:** 0.1.0
+**Lib-ID:** lib-core.inventory-list-display-test
+**Role:** test
+**Requires:** lib-core.inventory-list-display v0.1.0, lib-core.inventory-list v0.1.0, lib-core.composition v0.2.0
+
+## Running
+
+```bash
+export PATH="/c/msys64/mingw64/bin:$PATH"
+cd ~/Projects/Sporel/sporel-engine
+SPOREL_LIBS_DIR=~/Projects/Sporel/sporel-libs SPOREL_CI=1 SPOREL_LOG_STDERR=1 \
+    ./build/Sporel.exe --test-libs=lib-core.inventory-list-display-test 2>&1 | tail -15
+```
+
+Expected: `pass=N fail=0` where N >= 9.
+
+## Assertions
+
+1. `create` returns widget_def with `render`, `handle_input`, and correct `title`
+2. `create` with a non-container entity loud-errors
+3. `register_action` + `unregister_action` round-trip completes without error
+4. Duplicate action label loud-errors
+5. Non-function callback loud-errors
+6. Default action-set is empty; `unregister_action` on unknown label is a no-op
+7. `_test_get_rows` returns items in `inventory.contents` order
+8. Default icon-resolver reads `sprite_atlas` and `sprite_uv.*` from item properties
+9. Custom icon-resolver is invoked after `set_icon_resolver`