cmake : introduce semantic versioning (#26839)

* cmake : introduce semantic versioning (wip)

This commit introduces semantic versioning to llama.cpp.

* squash! cmake : introduce semantic versioning (wip)

* cmake : update test-cmake README notes [no ci]

* include libmtmd in output so show its semversioned

* ci : add make-release workflow

* ci : fix build number check in build-cmake-pkg.yml

* examples : remove trailing whitespace

* ci : abort if upstream ggml version does not exist

* ci : extract step contents into scripts

* ci : add GGML_NATIVE=OFF to ubuntu job

* examples : remove CI build information from test-cmake [no ci]

This commit removes the nightly/release information that I added
previously to keep this focused only on using building and installing
llama.cpp with cmake and being able to quickly verify changes or
troubleshoot issues.

* ci : merge scripts into single script

* remove -dev-build_number support

This commit removes the incremental build number (versioning) support
that I added. This was incorrect and we should only use the semver for
the version. Releases will be tag a nightly build and package
maintainers/managers that build from source can use the tag and it is
therefor important that the correct version is reported. So a
nightly-build will report the semver without the build number. The build
number and commit as availble via cmake and test-cmake has been updated
to include an example of using them:
```console
$ ./build.sh
[test-cmake] version: 0.1.0, build: 10360 (08c69e381)
...
```

Refs: https://github.com/ggml-org/llama.cpp/pull/26839#discussion_r3755836969

* docs: add initial release.md documentation

* cmake : clean-up and add LLAMA_BUILD_IS_DEV option

* ci : remove version input from make-release job

* ci : add LLAMA_BUILD_IS_DEV=OFF to build-cmake-pkg.yml

Refs: https://github.com/danbev/llama.cpp/actions/runs/31576801921/job/94050639145

* docs : update release notes with LLAMA_BUILD_IS_DEV info [no ci]

* ci : add TODO to winget workflow [no ci]

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

docs/release.md

@@ -0,0 +1,49 @@
+# Release process
+
+llama.cpp uses [semantic versioning](https://semver.org) (`MAJOR.MINOR.PATCH`).
+
+## Version bump guidelines
+
+| Change type | Version component |
+|---|---|
+| Breaking change to the public C API (`include/llama.h`)         | `MAJOR` |
+| Backward-compatible features, model support, or API addition    | `MINOR` |
+| Bug fix with no API change                                      | `PATCH` |
+
+The version is set in the three variables at the top of the root `CMakeLists.txt`:
+
+```cmake
+set(LLAMA_VERSION_MAJOR 0)
+set(LLAMA_VERSION_MINOR 1)
+set(LLAMA_VERSION_PATCH 0)
+```
+
+_A version bump should be included in the PR that introduces the change, or in a
+dedicated bump commit merged before the release is cut._
+
+_TODO: add PR labels (`semver: patch`, `semver: minor`, `semver: major`) to help
+identify which PRs require a version bump before cutting a release._
+
+## Making a release
+
+Releases are created by running the [make-release](.github/workflows/make-release.yml)
+which is a manual workflow.
+
+The workflow creates an annotated git tag (e.g. `v0.1.0`) and pushes it to the
+remote. No GitHub Release object is created, the tag is the release artifact.
+
+## Building a release
+
+By default, `LLAMA_BUILD_IS_DEV=ON` which appends a `-dev` suffix to `LLAMA_VERSION`,
+marking the build as a nightly/development build. Distributors building from a
+release tag must pass `-DLLAMA_BUILD_IS_DEV=OFF` to produce a clean version string
+(e.g. `0.1.0` instead of `0.1.0-dev`).
+
+## How releases reach users
+Currently releases are not published to github releases, only nightly/development
+builds are available there. The way users can access releases are using the following
+channels:
+
+- **llama-install.sh**  — downloads pre-built binaries built from the release tag.
+- **Package managers**  — consume the git tag directly.
+- **Build from source** — users clone the repo and check out the tag.