docs: refresh model-selection guidance to the Claude 5 families (#2723)

Model-routing guidance across the rules, skills, and harness-steering docs
still recommends Sonnet 4.6 / Opus 4.5-4.6 by name. Readers on the current
generation have to map those onto Sonnet 5 / Opus 5 themselves, and the
recommendation reads as pinned to a superseded generation.

Renames the recommended models in guidance tables and updates two pinned
model IDs in code samples:

- rules/steering guidance: .cursor, .kiro, and the seven translated
  performance.md copies (ja-JP, zh-CN, zh-TW, ko-KR, pt-BR, es, tr)
- skills/prompt-optimizer complexity-routing table (+ zh-CN copy)
- skills/cost-aware-llm-pipeline MODEL_SONNET constant (+ zh-CN, ja-JP)
- docs/examples project-guidelines template, which pinned the invalid ID
  claude-sonnet-4-5-20250514 (+ zh-TW, ja-JP copies)

Deliberately left alone:

- The "Pricing Reference (2025-2026)" table in cost-aware-llm-pipeline.
  Renaming those rows while keeping the existing per-token figures would
  assert Claude 5 pricing this change has not verified.
- Executable model config (.opencode/opencode.json, agent.yaml). Those pins
  change real agent behavior and belong in their own reviewed change.
- Historical and illustrative references: the-shortform-guide session
  transcripts, the ECC-PRO roadmap log entry, gan-style-harness's
  "Opus 4.5-class"/"Opus 4.6-class" capability tiers, and
  strategic-compact's deliberately generic "400k Opus 4.x" example.
- docs/ATLAS-CLOUD-GUIDE.md, which lists a third-party provider's catalog.

Documentation wording only; no behavioral change.

Co-authored-by: Phumchai Tanonsi <274848436+phumchai1515-prog@users.noreply.github.com>

docs/examples/project-guidelines-template.md

@@ -161,7 +161,7 @@ async def analyze_with_claude(content: str) -> AnalysisResult:
     client = Anthropic()
 
     response = client.messages.create(
-        model="claude-sonnet-4-5-20250514",
+        model="claude-sonnet-5",
         max_tokens=1024,
         messages=[{"role": "user", "content": content}],
         tools=[{