refactor(search): remove NLP/smart-search feature entirely (#772)

## Summary

- Removes the NLP/smart-search feature completely — the feature was too unreliable and slow; users get better results with the regular search filters
- Deletes the entire backend `search/` package (NlSearchController, NlQueryParserService, NlpClient, NlSearchRateLimiter — 14 classes + 6 test classes)
- Deletes the `nlp-service/` Python microservice (FastAPI, rapidfuzz, DB-backed person matching)
- Removes all frontend NL search components: SmartModeToggle, SmartSearchStatus, InterpretationChipRow, DisambiguationPicker, chip-types, theme-chip-removal
- Strips smart-mode logic from SearchFilterBar and documents/+page.svelte
- Removes `SMART_SEARCH_UNAVAILABLE` / `SMART_SEARCH_RATE_LIMITED` error codes from backend, frontend types, and all three i18n files (de/en/es)
- Removes `nlp-service` container and `APP_NLP_BASE_URL` from both docker-compose files
- Removes Ollama/NLP Prometheus scrape job and Grafana dashboard
- Deletes ADRs 028 (×2), 034, 035

## Test plan

- [ ] Backend compiles: `cd backend && ./mvnw compile -q` → BUILD SUCCESS
- [ ] Frontend server tests pass: `cd frontend && npm run test -- --project=server`
- [ ] No NLP/smart-search references remain in source: `grep -r "SmartSearch\|NlSearch\|nlp-service\|SMART_SEARCH" backend/src frontend/src`
- [ ] `docker compose config` validates both compose files
- [ ] Search page loads, filter bar works, no smart-mode toggle visible

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Marcel <marcel@familienarchiv>
Reviewed-on: #772

frontend/messages/en.json

@@ -22,33 +22,6 @@
 	"error_forbidden": "You do not have permission for this action.",
 	"error_csrf_token_missing": "Session error. Please reload the page.",
 	"error_too_many_login_attempts": "Too many login attempts. Please try again later.",
-	"error_smart_search_unavailable": "The smart search is currently unavailable. Please use the regular search.",
-	"error_smart_search_rate_limited": "You have used the search function too frequently. Please wait a minute.",
-	"smart_search_keywords_not_applied": "Keywords could not be applied to this search.",
-	"search_toggle_smart_label": "AI",
-	"search_toggle_smart_label_suffix": " search",
-	"search_toggle_keyword_label": "Text",
-	"search_toggle_keyword_label_suffix": " search",
-	"search_loading_nl": "Querying the archive…",
-	"search_loading_nl_sub": "The AI is analysing your request. This can take up to 15 seconds.",
-	"search_error_unavailable": "Smart search unavailable",
-	"search_error_unavailable_body": "The AI search is currently unreachable. You can repeat your request as a plain full-text search.",
-	"search_switch_to_keyword": "Switch to full-text search",
-	"search_error_rate_limited": "Too many requests",
-	"search_error_rate_limited_body": "You have used the smart search too frequently. Please wait a minute and try again.",
-	"search_empty_nl": "No results",
-	"search_empty_retry_keyword": "Repeat as full-text search",
-	"search_filter_remove_label": "Remove filter: {label}",
-	"search_chip_sender": "Sender",
-	"search_chip_date": "Period",
-	"search_chip_keyword": "Keyword",
-	"search_chip_theme_prefix": "Topic",
-	"search_chip_directional_label": "From {from} to {to}, remove filter",
-	"search_disambiguation_trigger_label": "Several people found — click to choose",
-	"search_disambiguation_cue": "(choose…)",
-	"search_disambiguation_heading": "Choose a person",
-	"search_disambiguation_did_you_mean": "Did you mean {name}?",
-	"search_disambiguation_select_label": "Select {name}",
 	"error_validation_error": "The input is invalid.",
 	"error_internal_error": "An unexpected error occurred.",
 	"nav_documents": "Documents",