feat(setup): apply per-role LLM model presets, remove --llm-model (#268)

* feat(setup): write per-role llm model presets

* feat(setup): remove llm model setup flag

* chore(setup): update llm preset guidance

* docs(setup): document llm model presets

* chore(release): sync uv.lock to 0.9.0

* fix(cli): make sl query --execute work on secret-backed connections

sl query --execute used a parallel SQL executor (createDefaultLocalQueryExecutor)
that passed connection.url verbatim into pg, so file:/env: secret references
failed with "SASL: SCRAM-SERVER-FIRST-MESSAGE: client password must be a string".

Collapse onto the connector-based executor already used by MCP and ingest
(createKtxCliIngestQueryExecutor), which resolves secret references and supports
every driver. Delete the now-dead local/postgres/sqlite query executors, their
tests, and the orphaned hasLocalQueryExecutor driver flag.

* docs(agents): require one implementation per capability

Add a design-reasoning default and a matching self-check question telling agents
to route callers through a single shared implementation of a capability rather
than forking a parallel one, and to fix the shared layer rather than patch one
branch. Encodes the lesson from a divergent SQL-execution-path bug, stated
generally.

CLAUDE.md is a symlink to AGENTS.md, so both agent-instruction files are covered.

docs-site/content/docs/configuration/ktx-yaml.mdx

@@ -377,6 +377,10 @@ llm:
   models:
     default: claude-sonnet-4-6
     triage: claude-haiku-4-5
+    candidateExtraction: claude-sonnet-4-6
+    curator: claude-opus-4-7
+    reconcile: claude-opus-4-7
+    repair: claude-haiku-4-5
   promptCaching:
     enabled: true
     systemTtl: 1h
@@ -404,6 +408,11 @@ llm:
     backend: codex
   models:
     default: gpt-5.5
+    triage: gpt-5.5
+    candidateExtraction: gpt-5.5
+    curator: gpt-5.5
+    reconcile: gpt-5.5
+    repair: gpt-5.5
 ```
 
 ### Model roles
@@ -643,6 +652,11 @@ llm:
     backend: claude-code
   models:
     default: sonnet
+    triage: haiku
+    candidateExtraction: sonnet
+    curator: opus
+    reconcile: opus
+    repair: haiku
 ingest:
   adapters:
     - live-database