chore: add Codex project context and agent guidance

.agents/skills/kst4contest-change/references/settings-and-data.md

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+# Settings and data context
+
+Inspect `Config`/settings classes and current UI before using these names; this list records important settings/concepts encountered during prior work.
+
+## Band / station settings
+
+Important concepts have included:
+
+- `MYQRGFirstCat`;
+- `MYQRGSecondCat`;
+- manual station band information;
+- current/actual QTF;
+- known-active bands;
+- selected/current QRG.
+
+Band-dependent features must use the correct category/station context.
+
+## Antenna / path settings
+
+Important concepts have included:
+
+- `actualQTF`;
+- `antennaBeamWidthDeg`;
+- maximum QRB;
+- AirScout/path-analysis settings.
+
+Missing QRB/QTF must remain unknown, not numeric zero.
+
+## UI settings
+
+Persisted UI behaviour has included:
+
+- dark mode;
+- map/path-analysis visibility;
+- filters/reachability controls;
+- column visibility;
+- divider/layout state where implemented.
+
+Do not reset persisted user choices as an incidental effect of a feature change.
+
+## Logging / worked persistence
+
+Worked information is persisted and updated through multiple input paths.
+
+Before changing one path, compare semantics across:
+
+- DB load on startup;
+- simple/manual log integration where present;
+- UCXLog/DXLog;
+- Win-Test;
+- other current logging inputs.
+
+The goal is one worked-state interpretation regardless of source.
+
+## Chat/message automation
+
+Configuration has included:
+
+- beacon/autoanswer enablement;
+- beacon defaults;
+- message limits/timers;
+- category-specific communication.
+
+Do not duplicate timers or create per-feature scheduling that bypasses the shared safety model.
+
+## Connection state
+
+Connection-state UI must reflect actual ON4KST connection lifecycle.
+
+Any new state enum/property should have a clear owner and thread boundary.
+
+## Persistence rule
+
+Do not change persisted keys/schema/semantics simply to make new code easier.
+
+If a schema/key migration is required:
+
+1. explain current and new format;
+2. describe backward compatibility;
+3. ask for approval before implementing.