chore: add reference docs, scripts, tests, demo, prototypes

- Reference docs: known issues, user journey, location redesign, mission merge plan
- Scripts: fill_location_state, merge_missions, migrate_location, migrate_state
- Tests: e2e test suite, asset entries unit tests
- Demo: location board, hifi prototypes, test screenshots
- Data backup: asset log entries and state nodes
- Update .gitignore

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

reference/known_issues_post_merge.md

@@ -0,0 +1,40 @@
+# Known Issues — Schema Migration + Mission Merge (2026-05-31)
+
+## P0 — Logic Errors
+
+1. `_entry_state_label()` aggregates ALL unique labels from all state nodes in an interval, rather than returning the most recent one at simulation time.
+   - Merged entries show "Transfer; Exploration" instead of the time-correct state.
+
+2. `_entry_location()` returns the FIRST state node's location (by time), not the most recent one.
+
+3. Merged entries' `state_label` field contains semicolons from `merge_group()`, producing "Transfer > Exploration" via `_display_multi_value_text()`.
+
+## P1 — Missing Data Display
+
+4. Detail page entry table: location and state_label columns are empty (fields dropped from `asset_log_entries`).
+
+5. Timeline: state_labels array is always empty — data isn't propagated from state nodes.
+
+6. Location board: state grouping is broken for ST-01/ST-02/XH-01/XH-02 due to aggregated labels.
+
+## P2 — Form / Edit
+
+7. Event point location is a free-text input instead of dropdown, and value is lost on submit.
+
+8. Edit form: state node location/state dropdowns may not be pre-populated correctly.
+
+## P3 — Data Quality
+
+9. Star Port Station state_label has encoding issues (Chinese garbled text).
+
+10. Some auto-migrated state nodes have raw titles as state_label (e.g. "Reconfiguring to ST-02").
+
+## P4 — Architecture
+
+11. Solar Shuttle 2/3 show "No Active Interval" at 2060-08-11 — needs investigation.
+
+---
+
+## Resolution Status
+
+- P0-P4: Documented 2026-05-31. To be addressed after state/location redesign.