docs(pgserver): Phase 7 — bootstrap example + CI gate documentation

Wraps the v1.0 PG-wire deliverable with the two pieces operators
actually look for: a runnable example PRG and an updated CI gate
list in CLAUDE.md.

* examples/pgserver_demo.prg — full bootstrap PRG demonstrating
  every HB_FUNC composed in the order a production deployment
  needs:
    PG_TLS_SELF_SIGNED → PG_ADD_ROLE × N → PG_ALLOW_IP × N →
    PG_SERVER_START( ":5432", "md5" )
  Comments cover the SHARED-DBF integration point and the SPAWN
  idiom for non-blocking server startup. Builds cleanly under
  the examples_build sweep (now 66/72; was 65/71).

* CLAUDE.md — the "어떤 파일이든 수정한 후" mandatory test list
  goes from 3 gates → 6:
    1. go test ./...
    2. FiveSql2 SQL:1999 43/43
    3. Harbour compat 56/56
    4. std.ch 17/17 (added)
    5. FRB 7/7 (added)
    6. pgserver integration 6/6 (added — psql required)
  Aligns the rule-of-thumb with reality. The five suites already
  ran on every audit-era commit; pgserver/run.sh is new in
  Phases 3-6 and now joins them.

This completes the v1.0 PostgreSQL-wire frontend. End-to-end
checklist:

  Phase 1: per-session state isolation         [93cf5c8]
  Phase 2: SimpleQuery wire MVP                [d98f5e1 7083297]
  Phase 3: DML + transactions                  [a556764]
  Phase 4: Extended Protocol (Parse/Bind/Exec) [8472928]
  Phase 5: password + MD5 auth                 [90eafcf]
  Phase 6: TLS + IP allowlist                  [3b2dd36]
  Phase 7: example + docs                      [this commit]

Open follow-ups (Phase 7.x):
  - hbrdd workarea per-thread isolation (audit Top-Risk #2):
    ≥3 concurrent connections doing in-flight INSERT/SELECT in
    their own transactions can race at the workarea layer. Fix
    is a separate workstream against hbrtl/database.go +
    hbrdd/dbf/. Documented limitation in tests/pgserver/run.sh.
  - SCRAM-SHA-256 auth (Phase 5.1).
  - pg_catalog shim for BI-tool introspection (Phase 1.1+ of the
    original audit plan).
  - Binary parameter format for NUMERIC/TIMESTAMP (Phase 4.1).

All gates green:
  go test ./...               ✓
  FiveSql2 SQL:1999 43/43     ✓
  Harbour compat 56/56        ✓
  std.ch 17/17                ✓
  FRB 7/7                     ✓
  examples 66/72              ✓ (+1 from new pgserver_demo)
  pgserver integration 6/6    ✓

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -2,7 +2,7 @@
 
 ## 절대 규칙: 변경 후 반드시 검증
 
-**어떤 파일이든 수정한 후, 다음 3개 테스트를 모두 통과해야 한다.**
+**어떤 파일이든 수정한 후, 다음 6개 테스트를 모두 통과해야 한다.**
 하나라도 실패하면 해당 변경을 되돌린다.
 
 ```bash
@@ -13,8 +13,17 @@ go test ./...
 ./five build _FiveSql2/test/test_sql1999.prg _FiveSql2/src/*.prg -o /tmp/test_sql
 cd ~/tmp && rm -f *.dbf __cte_*.dbf && /tmp/test_sql
 
-# 3. Harbour 호환 테스트 (51/51)
+# 3. Harbour 호환 테스트 (56/56)
 ./five build tests/compat_harbour.prg -o /tmp/test_compat && /tmp/test_compat
+
+# 4. std.ch 테스트 (17/17)
+bash tests/std_ch/run.sh
+
+# 5. FRB 테스트 (7/7)
+bash tests/frb/run.sh
+
+# 6. pgserver 통합 테스트 (6/6) — psql 필요
+bash tests/pgserver/run.sh
 ```
 
 **절대로 "나중에 확인" 하지 않는다. 매 변경마다 즉시.**