refactor(ui): atlas review warnings — headers, public API, KEY_N, overlay source of truth (#128)

4. AtlasPanel and AtlasViewer now compose their title + hint from an
   ImplantHeader child rather than hand-rolling them via draw_string, so the
   D-169 "theme swap changes the implant hardware appearance" invariant
   holds end-to-end. _refresh_screen_header() drives content per level and
   on system navigation.

5. AtlasViewer exposes city_canvas_pos(), get_hovered_city(),
   get_selected_city(), and get_overlay_defs() as public API — the marker
   overlay no longer reaches into underscore-prefixed state, which is
   especially important because viewer is an untyped var in the overlay.

6. KEY_N now consumes unconditionally while the viewer is visible, and
   main.gd's global economics-monitor toggle is gated on
   !HudGroups.is_app_active("implant/map/atlas"). Previously pressing N
   without a selected city fell through and closed the fullscreen atlas as
   a side effect.

7. OVERLAY_DEFS lives in AtlasViewer as the single source of truth.
   AtlasOverlayBar reads the list via viewer.get_overlay_defs(), and
   AtlasViewer derives _overlay_visibility / _overlay_locked from the same
   table at _ready() — no more hand-maintained parallel lists, so the bar
   and the guard in set_overlay_visible can't drift.

8. AtlasOverlayBar drops `class_name`: it now loads via
   load("res://ui/implant/atlas_overlay_bar.gd") from AtlasViewer, the same
   pattern AtlasPanel uses for AtlasViewer. _init(viewer_ref = null) keeps
   the required-arg footgun off the editor's introspection path.

9. `star-map-data` make target added to regenerate
   client/data/star_map_data.json from systems.db + wiki, and
   `check-star-map` wired into pre-pr-validate + pre-pr-client so any
   commit that touches the generator (or any downstream systems.db change
   like server #839) fails pre-pr until the JSON is regenerated. The
   terrain_reference data-availability dependency is no longer tribal
   knowledge.

Also addresses review #15 (push_warning on unknown overlay id in
set_overlay_visible) and #16 (disabled always-on buttons drop handler
churn) as part of the same refactor.

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 check-star-map \
+       checklist-validate checklist-generate check-star-map star-map-data \
        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 \
@@ -53,6 +53,8 @@ help:
 	@echo "  make validate-content   Validate content YAML against schemas"
 	@echo "  make check-fact-ids    Check fact_id references against knowledge catalogs"
 	@echo "  make atlas-verify      Verify atlas proposal JSONs (all in docs/atlas/proposals/)"
+	@echo "  make star-map-data     Regenerate client/data/star_map_data.json from systems.db + wiki"
+	@echo "  make check-star-map    Assert star_map_data.json is up to date (part of pre-pr-client)"
 	@echo "  make economy-db        Import economics data into systems.db (TOML/JSON → SQLite)"
 	@echo "  make fixtures-client    Generate GDScript->Rust cross-encoder fixtures (#475)"
 	@echo "  make golden-diff        Show diff if golden file output has changed"
@@ -260,7 +262,7 @@ pre-pr-build: build-server build-client
 pre-pr-test: test-server test-client
 	@echo "--- Tests: PASS ---"
 
-pre-pr-validate: validate-content check-fact-ids
+pre-pr-validate: validate-content check-fact-ids check-star-map
 	@echo "--- Content validation: PASS ---"
 
 pre-pr-fixtures:
@@ -302,7 +304,7 @@ pre-pr-fixtures:
 pre-pr-server: lint-server build-server test-server pre-pr-fixtures audit
 	@echo "=== Server pre-PR: PASSED ==="
 
-pre-pr-client: lint-client build-client test-client
+pre-pr-client: lint-client build-client test-client check-star-map
 	@echo "=== Client pre-PR: PASSED ==="
 
 pre-pr-content: validate-content check-fact-ids checklist-validate atlas-verify
@@ -375,6 +377,14 @@ checklist-generate:
 check-star-map:
 	@python3 tooling/generate-star-map-data.py --check
 
+# Regenerate client/data/star_map_data.json from systems.db + wiki. Depends on
+# nothing — call this after any systems.db change (e.g. the server atlas
+# pipeline populating terrain_reference in #839) so the atlas viewer picks up
+# the new fields. pre-pr-client / pre-pr-validate assert staleness via
+# check-star-map and will fail if this step is skipped.
+star-map-data:
+	@python3 tooling/generate-star-map-data.py
+
 perf-baseline:
 	@tooling/perf-baseline