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]>

src/io/recovery.rs

@@ -255,6 +255,7 @@ impl RecoveryReport {
         lines.push(format!("Report schema: {}", REPORT_SCHEMA_VERSION));
         lines.push(format!("Report ID: {}", self.report_id));
         lines.push(format!("Application version: {}", env!("OCS_APP_VERSION")));
+        lines.push(format!("Application build: {}", env!("OCS_FULL_VERSION")));
         lines.push(format!("Application revision: {}", env!("OCS_GIT_REV")));
         lines.push(format!("Build profile: {}", env!("OCS_BUILD_PROFILE")));
         lines.push(format!("Build features: {}", env!("OCS_BUILD_FEATURES")));