Update release notes: 33 reports, amcheck corruption checks, m1 rename

Author: NikolayS

RELEASE_NOTES.md

@@ -1,10 +1,28 @@
 # postgres_dba 7.0
 
-**30 reports** | Tested on **PostgreSQL 13–18** | Works with `pg_monitor` role
+**33 reports** | Tested on **PostgreSQL 13–18** | Works with `pg_monitor` role
 
 ## New Reports
 
-### c1 — Buffer cache contents
+### Corruption checks (c1, c2, c3) — powered by `amcheck`
+
+Three levels of integrity checking, all requiring `CREATE EXTENSION amcheck`:
+
+| Report | Lock | What it checks | When to use |
+|--------|------|----------------|-------------|
+| **c1** | AccessShareLock | B-tree pages, GIN indexes (PG18+), heap+TOAST (PG14+) | **Production primary** — safe, non-blocking |
+| **c2** | ShareLock ⚠️ | B-tree parent-child ordering, sibling pointers, rootdescend, checkunique (PG14+) | **Clones or standbys** — detects glibc/collation corruption |
+| **c3** | ShareLock ⚠️⚠️ | Everything in c2 + heapallindexed + verify_heapam with full TOAST | **Clones only** — proves every heap tuple is indexed, slow on large DBs |
+
+All three check system catalog indexes (`pg_catalog`, `pg_toast`) — because catalog corruption is the scariest kind.
+
+Robustness:
+- Graceful handling when `amcheck` extension is not installed
+- No false corruption reports on insufficient privileges (reports skipped count)
+- Version-conditional: uses appropriate function signatures for PG11–18
+- GIN support via `gin_index_check()` on PostgreSQL 18+
+
+### m1 — Buffer cache contents
 What's in your `shared_buffers` right now. Shows cached size vs total size, % of cache used per object, and dirty buffer counts. Requires `pg_buffercache` extension.
 
 ### s3 — Workload profile by query type
@@ -24,14 +42,14 @@ Categories reorganized for consistency:
 
 | Old | New | Reason |
 |-----|-----|--------|
-| b6 | **c1** | Buffer cache isn't bloat — moved to new **c** (cache) category |
+| b6 | **m1** | Buffer cache → **m** (memory) category |
 | c1 | **p1** | Index creation progress → **p** (progress) category |
 | p1 | **x1** | Alignment padding (experimental) → **x** (experimental) category |
 
 ## Bug Fixes
 
 - **i3**: Fixed `operator is not unique` error when `intarray` extension is installed (added explicit `::int2[]` cast)
-- **s1, s2**: Fixed `blk_read_time does not exist` error on PostgreSQL 17+ (`blk_read_time`/`blk_write_time` renamed to `shared_blk_read_time`/`shared_blk_write_time` in pg_stat_statements 1.11)
+- **s3**: Fixed `function round(double precision, integer) does not exist` — added `::numeric` casts
 - **i2**: Removed unused `redundant_indexes_grouped` CTE (dead code)
 - **s1**: Removed duplicate `sum(calls)` in the pre-PG13 code path
 
@@ -51,10 +69,10 @@ Categories reorganized for consistency:
 ## CI Improvements
 
 - Added `PAGER=cat` to all `psql` invocations (prevents pager hangs)
-- Added `intarray` and `pg_buffercache` extensions to test matrix
+- Added `intarray`, `pg_buffercache`, and `amcheck` extensions to test matrix
 - Added foreign key test tables for i3 regression testing
 - Added dedicated i3 regression test with `intarray` installed
 
 ## Compatibility
 
-Tested on PostgreSQL 13, 14, 15, 16, 17, and 18 — all 30 reports pass with both superuser and `pg_monitor` roles.
+Tested on PostgreSQL 13, 14, 15, 16, 17, and 18 — all 33 reports pass with both superuser and `pg_monitor` roles.