docs: cut CHANGELOG into versioned entries, refresh ReleaseNotes

Doc hygiene catch-up surfaced by the PR #62 review:

- CHANGELOG.md: the [Unreleased] section had accumulated all post-preview
  work without ever being cut into release entries. Promote it into:
    - [0.1.3] - new fixes from #58 (DiskSize normalization) and #59
      (HttpClient -TimeoutSeconds + RequestTimeout surfacing)
    - [0.1.2] - #43/#44/#45 fixes from PR #46
    - [0.1.1] - the cmdlet expansion + OpenAPI validation that
      actually shipped to PSGallery as 0.1.1
  Reset [Unreleased] to empty.

- src/PSProxmoxVE/PSProxmoxVE.psd1: replace the stale "Initial preview
  release" ReleaseNotes (carried over since 0.1.0-preview) with actual
  0.1.3 notes. PSGallery shows this on the version page.

- CLAUDE.md: document the release process so future bumps update the
  psd1 version, psd1 ReleaseNotes, and CHANGELOG together before the
  tag is cut. Prevents this hygiene gap from recurring.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/PSProxmoxVE/PSProxmoxVE.psd1

@@ -371,7 +371,21 @@
             ProjectUri   = 'https://github.com/goodolclint/PSProxmoxVE'
 
             # Release notes for this version
-            ReleaseNotes = 'Initial preview release. Supports PVE 8.x and 9.x with VM, container, storage, network, SDN, user/role/permission, template, cloud-init, snapshot, and task management.'
+            ReleaseNotes = @'
+## 0.1.3
+
+Fixed:
+- New-PveVm -DiskSize / New-PveContainer -RootFsSize normalize unit suffixes
+  (32G, 1T, etc.) to bare GiB before sending to PVE so the documented call
+  shape works on LVM/LVM-thin storages (#58).
+- HttpClient timeouts are now configurable via -TimeoutSeconds on
+  Connect-PveServer (session default), Send-PveFile, and
+  Invoke-PveStorageDownload (per-call, 30-minute implicit default).
+  Timeouts surface as PveApiException(RequestTimeout) instead of a raw
+  TaskCanceledException (#59).
+
+Full changelog: https://github.com/goodolclint/PSProxmoxVE/blob/main/CHANGELOG.md
+'@
 
         }