addrkit: strict ordinal matching, LLM-variant guard, externalized prompt

- match: require candidate ordinal to equal the query ordinal in fuzzy search
  (deterministic typo recall 73% -> 80%, no wrong houses)
- resolver: compatibleVariant guard — LLM may only fix street spelling, keeping
  the same words, ordinal and house unit; damerau distance for transpositions
- llm: prompt moved out of code (go:embed default_prompt.txt) with
  llm.system_prompt / llm.system_prompt_file overrides; guided JSON parsing
  tolerant of thinking blocks
- address: recognize ordinals appearing after the street name
- tests: first coverage for the LLM adapter and config prompt loading; README

Measured (sample 200): deterministic 94.7-95.8% exact / 0 wrong across 4 seeds;
LLM+guard typo 90.7-89.8% / 0 wrong. LLM fallback latency ~1.2-1.9s.

dev/config.llm.json

@@ -0,0 +1,8 @@
+{
+  "addr": "127.0.0.1:6172",
+  "data_path": "dev/registry.db",
+  "log_level": "warn",
+  "resolve": { "fuzzy_threshold": 0.82, "ambiguity_margin": 0.06, "max_candidates": 5 },
+  "portal": { "url": "https://map.novo-sibirsk.ru/elitegis/rest/services/maps/disconnections/MapServer/101/query", "timeout_seconds": 2, "retries": 0 },
+  "llm": { "enabled": true, "url": "http://127.0.0.1:6193", "token": "EMPTY", "model": "qwen3-14b-awq", "timeout_seconds": 5, "max_tokens": 512, "disable_thinking": true }
+}