Add PGXN packaging: META.json, publishing CI, install + release docs

- META.json (PGXN Meta Spec 1.0.0): name, abstract, version 0.1.0, maintainer
  David Bitner <bitner@dbspatial.com>, MIT license, provides/prereqs/resources,
  release_status testing.
- .github/workflows/release.yml: on a v* tag, validate+bundle+upload to PGXN via
  pgxn/pgxn-tools (needs PGXN_USERNAME / PGXN_PASSWORD secrets); guards that the tag
  matches META.json version.
- .gitattributes: keep PLAN.md and .github/ out of the published tarball.
- README: PGXN + CI badges, an Installation section (pgrx/cargo-pgrx, not PGXS), and
  a maintainer Releasing section.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: bitner

.gitattributes

@@ -0,0 +1,3 @@
+PLAN.md export-ignore
+.github/ export-ignore
+/.gitattributes export-ignore

.github/workflows/release.yml

@@ -0,0 +1,43 @@
+name: Release to PGXN
+
+# Publishes a release to the PostgreSQL Extension Network (https://pgxn.org) when a
+# version tag is pushed. Requires two repository secrets, from a PGXN Manager account
+# (https://manager.pgxn.org): PGXN_USERNAME and PGXN_PASSWORD.
+#
+# To cut a release:
+#   1. Bump "version" in Cargo.toml and META.json (keep them identical).
+#   2. Commit, then tag:  git tag v0.1.0 && git push origin v0.1.0
+# The tag (without its leading "v") must match the META.json version.
+
+on:
+  push:
+    tags:
+      - "v*"
+
+jobs:
+  release:
+    name: Bundle and release on PGXN
+    runs-on: ubuntu-latest
+    container: pgxn/pgxn-tools
+    env:
+      PGXN_USERNAME: ${{ secrets.PGXN_USERNAME }}
+      PGXN_PASSWORD: ${{ secrets.PGXN_PASSWORD }}
+    steps:
+      - name: Check out the release tag
+        uses: actions/checkout@v4
+
+      - name: Verify META.json version matches the tag
+        run: |
+          meta="$(sed -n 's/^[[:space:]]*"version"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' META.json | head -1)"
+          tag="${GITHUB_REF_NAME#v}"
+          echo "META.json version: '$meta' ; git tag: '$tag'"
+          if [ "$meta" != "$tag" ]; then
+            echo "::error::META.json version ($meta) does not match the tag ($tag)"
+            exit 1
+          fi
+
+      - name: Validate META.json and bundle the distribution
+        run: pgxn-bundle
+
+      - name: Release on PGXN
+        run: pgxn-release

META.json

@@ -0,0 +1,51 @@
+{
+   "name": "pg_table_range",
+   "abstract": "Planning-time partition pruning by per-partition data ranges, including non-key columns",
+   "description": "pg_table_range prunes partitions at planning time from a compact per-partition summary of each column's actual data: its min/max range for btree-comparable scalar types, or a covering extent for range types and PostGIS geometry. Unlike native PostgreSQL partition pruning, it works on columns that are not the partition key. Summaries are stored in the index's own metapage and maintained incrementally on insert (like BRIN), so no REINDEX is needed, and pruning is conservative so results are always identical to running without it.",
+   "version": "0.1.0",
+   "maintainer": [
+      "David Bitner <bitner@dbspatial.com>"
+   ],
+   "license": "mit",
+   "provides": {
+      "pg_table_range": {
+         "abstract": "Planning-time partition pruning by per-partition data ranges, including non-key columns",
+         "file": "pg_table_range.control",
+         "docfile": "README.md",
+         "version": "0.1.0"
+      }
+   },
+   "prereqs": {
+      "runtime": {
+         "requires": {
+            "PostgreSQL": "16.0.0"
+         }
+      }
+   },
+   "resources": {
+      "homepage": "https://github.com/bitner/pg_table_range",
+      "bugtracker": {
+         "web": "https://github.com/bitner/pg_table_range/issues"
+      },
+      "repository": {
+         "url": "git://github.com/bitner/pg_table_range.git",
+         "web": "https://github.com/bitner/pg_table_range",
+         "type": "git"
+      }
+   },
+   "generated_by": "David Bitner",
+   "meta-spec": {
+      "version": "1.0.0",
+      "url": "https://pgxn.org/meta/spec.txt"
+   },
+   "tags": [
+      "partitioning",
+      "partition pruning",
+      "performance",
+      "planner",
+      "brin",
+      "postgis",
+      "index access method"
+   ],
+   "release_status": "testing"
+}

README.md

@@ -2,6 +2,9 @@
 
 # pg_table_range: PostgreSQL data-range partition pruning
 
+[![PGXN version](https://badge.fury.io/pg/pg_table_range.svg)](https://pgxn.org/dist/pg_table_range/)
+[![CI](https://github.com/bitner/pg_table_range/actions/workflows/ci.yml/badge.svg)](https://github.com/bitner/pg_table_range/actions/workflows/ci.yml)
+
 A PostgreSQL 16+ extension that prunes partitions at planning time from a compact
 per-partition summary of each column's **actual data** — its min/max range for scalar
 columns, or its covering **extent** for range types and PostGIS geometry. This works on
@@ -26,6 +29,35 @@ without it.
 > [Scaling and partition count](#scaling-and-partition-count) for sizing. This is a
 > PostgreSQL limit on wide non-key access, not specific to this extension.
 
+## Installation
+
+This is a [pgrx](https://github.com/pgcentralfoundation/pgrx) (Rust) extension, so it is
+built and installed with `cargo pgrx` rather than a PGXS `make`. You need a Rust toolchain
+and `cargo-pgrx` matching the pgrx version this release pins (currently **0.18.1**):
+
+```sh
+cargo install cargo-pgrx --version 0.18.1 --locked
+
+# In a checkout of the source (from git or a PGXN download), install into the PostgreSQL
+# that `pg_config` points at. Match the feature flag to your server's major version:
+cargo pgrx install --release                                   # PostgreSQL 18 (default)
+cargo pgrx install --release --no-default-features --features pg17   # PostgreSQL 17
+cargo pgrx install --release --no-default-features --features pg16   # PostgreSQL 16
+```
+
+Use `--pg-config /path/to/pg_config` to target a specific PostgreSQL install. Then, in
+each database that should use it:
+
+```sql
+CREATE EXTENSION pg_table_range;
+```
+
+Supported: PostgreSQL 16, 17, and 18.
+
+The distribution is also published on [PGXN](https://pgxn.org/dist/pg_table_range/). Note
+that `pgxn install` (which expects a PGXS Makefile) does **not** apply here; use
+`pgxn download pg_table_range`, unzip, and run `cargo pgrx install` as above.
+
 ## Quick Start
 
 Summaries are built and maintained through a custom index access method, so pruning
@@ -282,6 +314,29 @@ PostGIS geometry test skips automatically where PostGIS is not installed; CI ins
 PostGIS so it runs there, and overlap pruning is also covered on every target by the
 range-type tests, which exercise the same code path.
 
+## Releasing (maintainers)
+
+The distribution is published to [PGXN](https://pgxn.org). Releases are automated by
+`.github/workflows/release.yml`, which runs on any `v*` tag and uses the
+[`pgxn/pgxn-tools`](https://github.com/pgxn/pgxn-tools) image to validate `META.json`,
+bundle the source, and upload it. One-time setup: add two repository secrets,
+`PGXN_USERNAME` and `PGXN_PASSWORD`, from a [PGXN Manager](https://manager.pgxn.org)
+account.
+
+To cut a release:
+
+1. Bump the version in **`Cargo.toml`** and **`META.json`** (keep them identical; the
+   `.control` file's `default_version` is filled from `Cargo.toml` at build time).
+2. Commit, then tag and push — the tag without its leading `v` must equal the
+   `META.json` version:
+
+   ```sh
+   git tag v0.1.0 && git push origin v0.1.0
+   ```
+
+`META.json` describes the PGXN distribution; `PLAN.md` and `.github/` are excluded from
+the published tarball via `.gitattributes`.
+
 ## Limitations
 
 - **Lock-table wall on many partitions.** Both `CREATE INDEX … USING table_range` and