fix(client): address PR #109 review — 6 warnings + 5 suggestions

Star map (W1-W3, S3):
- _process visibility guard + dirty flag (no redraw when hidden/unchanged)
- _system_hash masked to 31-bit positive range
- Extracted _find_nearest_system() shared helper

game_state.gd (W4):
- Inline load() in apply_snapshot() replaces per-tick overhead; safe at
  runtime because script is already in resource cache

Data pipeline (W5-W6):
- Script-relative path resolution via __file__
- --check mode + make check-star-map staleness target

Minor (S1-S2, S5):
- Removed redundant bone_idx assignment
- Simplified double-negative test assertion
- Documented autoload parse-order convention in CLAUDE.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Makefile

@@ -7,7 +7,7 @@ GODOT := $(shell command -v godot4 2>/dev/null || command -v godot 2>/dev/null)
        pre-pr pre-pr-lint pre-pr-build pre-pr-test pre-pr-validate pre-pr-fixtures \
        pre-pr-server pre-pr-client pre-pr-content \
        fixtures-client fixtures-gauntlet golden-diff golden-update \
-       checklist-validate checklist-generate \
+       checklist-validate checklist-generate check-star-map \
        build-sr-voice run-sr-voice test-voice-mock test-voice-real \
        perf-baseline debug-schedule \
        test-ipc-fixtures test-ipc-protocol test-ipc-integration test-ipc-benchmark \
@@ -347,6 +347,9 @@ checklist-validate:
 checklist-generate:
 	@tooling/validate-checklist
 
+check-star-map:
+	@python3 tooling/generate-star-map-data.py --check
+
 perf-baseline:
 	@tooling/perf-baseline