feat(obsidian): Bases 쿼리용 frontmatter 스키마 + 호스트 파일럿 3개

- dev/obsidian-schema.md: type별 frontmatter 규약 문서화
- infra/hosts/{incus-hp2,incus-kr1,zlambda}.md: 구조화된 필드로 파일럿 3개
- infra/hosts.base: Bases 쿼리 (전체/서울/K3s/유료/Critical 뷰)

기존 infra-hosts.md 본문은 그대로 유지. 파일럿 검증 후 나머지 호스트 확장 예정.

infra/hosts.base

@@ -0,0 +1,94 @@
+filters:
+  and:
+    - file.hasProperty("type")
+    - property("type") == "host"
+formulas:
+  display_ip: 'if(property("public_ip"), property("public_ip"), property("tailscale_ip"))'
+properties:
+  note.title:
+    displayName: 호스트
+  note.location:
+    displayName: 지역
+  note.host_kind:
+    displayName: 종류
+  note.provider:
+    displayName: 공급자
+  note.cpu_cores:
+    displayName: 코어
+  note.ram_gb:
+    displayName: RAM(GB)
+  note.k3s_role:
+    displayName: K3s
+  note.monthly_cost_usd:
+    displayName: 월비용($)
+  note.critical:
+    displayName: Critical
+  note.status:
+    displayName: 상태
+views:
+  - type: table
+    name: 전체 호스트
+    order:
+      - note.title
+      - note.location
+      - note.host_kind
+      - note.cpu_cores
+      - note.ram_gb
+      - note.k3s_role
+      - note.monthly_cost_usd
+      - note.status
+    sort:
+      - property: note.location
+        direction: ASC
+      - property: note.title
+        direction: ASC
+  - type: table
+    name: 서울 서버
+    filters:
+      and:
+        - property("location") == "seoul"
+    order:
+      - note.title
+      - note.host_kind
+      - note.cpu_cores
+      - note.ram_gb
+      - note.k3s_role
+      - note.critical
+    sort:
+      - property: note.ram_gb
+        direction: DESC
+  - type: table
+    name: K3s 노드
+    filters:
+      and:
+        - property("k3s_role") != null
+    order:
+      - note.title
+      - note.k3s_role
+      - note.location
+      - note.cpu_cores
+      - note.ram_gb
+      - note.lan_ip
+  - type: table
+    name: 유료 호스트 (월비용)
+    filters:
+      and:
+        - property("monthly_cost_usd") > 0
+    order:
+      - note.title
+      - note.provider
+      - note.location
+      - note.monthly_cost_usd
+      - note.status
+    sort:
+      - property: note.monthly_cost_usd
+        direction: DESC
+  - type: card
+    name: Critical 호스트
+    filters:
+      and:
+        - property("critical") == true
+    order:
+      - note.title
+      - note.location
+      - note.k3s_role