Report development builds as such, not as the release version

Only a release build (the commit tagged v<VERSION>, unchanged) gives a
version number. Others print 'dev <commit> (3 commits after v0.2.0-rc.1)',
from git describe (the Makefile's DESCRIBE), in jarld version,
jarl --version, jarl status, jarl whoami and the startup log; a build
without git says '(source build)'. The CLI's User-Agent and the footer's
tooltip follow suit, and /status's build gains since and ahead.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/development.md

@@ -232,17 +232,23 @@ runs it as a check before building.
 
 ### Which version a build reports
 
-The footer of the web UI, `jarld version` and `jarl --version` say what a
-binary was built from, linking to it on Gitea:
+The footer of the web UI, `jarld version`, `jarl --version`, `jarl status`
+and `jarl whoami` say what a binary was built from (the footer links to
+it on Gitea). Only a release build reports a version number:
 
 * **A release**: `make` run on the commit tagged `v<VERSION>` with no
   tracked file changed. The Makefile then sets `RELEASE_TAG`, and the
   footer reads "Powered by Jarl v0.2.0", linking to the release. The
   release workflow sets `RELEASE_TAG` itself.
-* **Any other build**: the commit, which Go records from git: "Powered by
-  Jarl 1a2b3c4d5e6f", linking to the commit. With uncommitted changes it
-  is marked `-modified`. The version commands print `0.2.0 (1a2b3c4d5e6f)`.
-* **No git** (a build from a source tarball): just `VERSION`.
+* **Any other build** is a development build, named by its commit (which
+  Go records from git) rather than `VERSION`: "Powered by Jarl
+  1a2b3c4d5e6f", linking to the commit. With uncommitted changes it is
+  marked `-modified`. The other places add where it stands relative to
+  the last tag, from `git describe` (the Makefile's `DESCRIBE`):
+  `dev 1a2b3c4d5e6f (3 commits after v0.2.0-rc.1)`, or
+  `dev 1a2b3c4d5e6f-modified (v0.2.0-rc.1 with uncommitted changes)`.
+* **No git** (a build from a source archive): `VERSION`, marked as such:
+  `0.2.0 (source build)`.
 
 `RELEASE_TAG=v0.2.0 make` forces the first case.