Show the exact build in About, Copy Info, REPORT and --version

Builds from main reported only the release version (2026.36) even when
HEAD was hundreds of commits past the tag. build.rs now also emits
OCS_TAG_DISTANCE, OCS_COMMIT_DATE, OCS_BUILD_METADATA and
OCS_FULL_VERSION: a clean checkout of the release tag stays "2026.36",
anything else becomes "2026.36+194.gef189d77", with ".dirty" appended
for uncommitted changes and only the hash when no tag can be counted
from (shallow clone, tarball). OCS_APP_VERSION is unchanged so the
update check, donation gate, User-Agents and window title keep working.

The About dialog gains Build / Commit date / Profile cards, Copy Info,
the REPORT issue template and recovery reports carry the full version,
and `-V`/`--version` print it instead of Cargo's 2026.36.0. Release
workflows check out full history so release binaries see the tag.

Also fixes the build being marked dirty when there is no repository:
diff-index exits 128 there, not 1.

Co-Authored-By: Claude Opus 5 <[email protected]>

.github/workflows/pages.yml

@@ -53,6 +53,9 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ steps.source.outputs.commit }}
+          # Full history so build.rs can measure the distance from the
+          # release tag; a shallow clone would label the build `+g<hash>`.
+          fetch-depth: 0
 
       - name: Validate release version
         env:

.github/workflows/release.yml

@@ -39,6 +39,9 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.commit || github.sha }}
+          # Full history so build.rs can measure the distance from the
+          # release tag; a shallow clone would label the build `+g<hash>`.
+          fetch-depth: 0
 
       - name: Validate package versions
         id: version
@@ -127,6 +130,9 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.commit || github.sha }}
+          # Full history so build.rs can measure the distance from the
+          # release tag; a shallow clone would label the build `+g<hash>`.
+          fetch-depth: 0
 
       - name: Validate package versions
         id: version
@@ -194,6 +200,9 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.commit || github.sha }}
+          # Full history so build.rs can measure the distance from the
+          # release tag; a shallow clone would label the build `+g<hash>`.
+          fetch-depth: 0
 
       - name: Validate package versions
         id: version
@@ -315,6 +324,9 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.commit || github.sha }}
+          # Full history so build.rs can measure the distance from the
+          # release tag; a shallow clone would label the build `+g<hash>`.
+          fetch-depth: 0
 
       - name: Validate package versions
         id: version