docs: correct supported floor to PostgreSQL 16

The extension supports PostgreSQL 16, 17, and 18 (16 is the floor: it has no
fetools support below 16). Correct the version statements from "14 and later"
to "16 and later" across the README and install guides, and update TODO to
reflect the completed 16/17/18 series.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: OffgridwithJD

README.md

@@ -22,7 +22,7 @@ Transparent Data Encryption offers encryption at the file level and solves the p
 
 This access method:
 
-- Works with upstream PostgreSQL 14 and later, patched with the `open_pg_tde` core patch (see [Installation](#installation))
+- Works with upstream PostgreSQL 16 and later, patched with the `open_pg_tde` core patch (see [Installation](#installation))
 - Uses extended Storage Manager and WAL APIs
 - Encrypts tuples, WAL and indexes
 - It **does not** encrypt temporary files and statistics **yet**
@@ -33,7 +33,7 @@ The documentation source is in [`documentation/`](documentation/). Start with th
 
 ## Installation
 
-`open_pg_tde` runs on upstream PostgreSQL 14 and later. You apply the `open_pg_tde` core patch to a PostgreSQL source tree, build it with the hooks enabled, and build the extension against that install. See [Install from source](documentation/docs/install-from-source.md) for the step-by-step guide, and [`patches/postgresql/README.md`](patches/postgresql/README.md) for the patch series and per-version status.
+`open_pg_tde` runs on upstream PostgreSQL 16 and later. You apply the `open_pg_tde` core patch to a PostgreSQL source tree, build it with the hooks enabled, and build the extension against that install. See [Install from source](documentation/docs/install-from-source.md) for the step-by-step guide, and [`patches/postgresql/README.md`](patches/postgresql/README.md) for the patch series and per-version status.
 
 ## Set up open_pg_tde
 

TODO.md

@@ -21,7 +21,7 @@ The patches live under `patches/postgresql/<major>/` and are applied with
 - [ ] **Encryption-aware frontend tools** (b): WAL/SMGR frontend integration for
       `open_pg_tde_rewind` / `open_pg_tde_basebackup`. Clears the `pg_rewind_*`,
       `pg_basebackup`, and upgrade tests.
-- [ ] Re-derive the series for PostgreSQL 14, 15, 16, 17.
+- [ ] Series done for 16, 17, 18 (extension floor is 16; 14/15 unsupported).
 
 ## Tests (required for each of the above)
 
@@ -36,7 +36,7 @@ The patches live under `patches/postgresql/<major>/` and are applied with
 
 - [ ] `patches/postgresql/README.md` kept current (apply, gate, maintenance).
 - [ ] User docs: replace the "Percona Server for PostgreSQL" install pages with
-      "apply the patch to PostgreSQL 14+ and build with `--enable-tde-hooks`".
+      "apply the patch to PostgreSQL 16+ and build with `--enable-tde-hooks`".
 - [ ] Architecture doc: the SMGR/WAL hook design and the gate.
 
 ## Core patch maintenance (ongoing)

documentation/docs/install-from-source.md

@@ -1,6 +1,6 @@
 # Install open_pg_tde on native PostgreSQL
 
-`open_pg_tde` runs on upstream PostgreSQL 14 and later. It does not require a
+`open_pg_tde` runs on upstream PostgreSQL 16 and later. It does not require a
 vendor fork of the server. Encryption is implemented through two extensibility
 points that upstream PostgreSQL does not yet expose: a pluggable storage
 manager for data files and a WAL storage manager for the write-ahead log.
@@ -19,7 +19,7 @@ PostgreSQL unless you enable the hooks.
 
 ## Prerequisites
 
-- A stock PostgreSQL 14+ source tree (a release tarball or a `REL_<major>_STABLE`
+- A stock PostgreSQL 16+ source tree (a release tarball or a `REL_<major>_STABLE`
   checkout).
 - A C toolchain, plus the usual PostgreSQL build dependencies.
 - OpenSSL development headers (`libssl-dev` / `openssl-devel`).

documentation/docs/install.md

@@ -1,14 +1,14 @@
 # Install open_pg_tde
 
-`open_pg_tde` runs on upstream PostgreSQL 14 and later. It does not require a
+`open_pg_tde` runs on upstream PostgreSQL 16 and later. It does not require a
 vendor fork of the server. Because encryption relies on storage-manager and WAL
 extensibility that upstream PostgreSQL does not yet expose, you install
 `open_pg_tde` by applying a gated core patch to a PostgreSQL source tree and
 building it, then building the extension against that install.
 
 === ":octicons-git-branch-16: From source (recommended)"
 
-    Apply the `open_pg_tde` core patch to a stock PostgreSQL 14+ source tree,
+    Apply the `open_pg_tde` core patch to a stock PostgreSQL 16+ source tree,
     build with the hooks enabled, and build the extension against it. This is the
     supported path and works on any platform that can build PostgreSQL.
 
@@ -25,7 +25,8 @@ building it, then building the extension against that install.
 | -------- | -------- |
 | 18 | Supported |
 | 17 | Supported |
-| 14 - 16 | Patch series in progress |
+| 16 | Supported |
+| 14 - 15 | Not supported |
 
 The core patch is maintained as a per-major-version series, since the storage
 manager interface changes between PostgreSQL majors. See