fix(framework/tools): eval injection, broken JSON, tmpfile leak (#548)

F-01 (HIGH): issue-edit.sh and issue-assign.sh used string interpolation
+ eval to build CLI commands. Replace all eval sites with Bash arrays so
user-supplied values (title, body, labels) are never shell-expanded.
For the Gitea path, replace get_gitea_repo_args() (which emits %q-escaped
strings designed for eval) with get_repo_slug() + get_gitea_login() so
repo/login are passed as properly-quoted array elements.

F-07 (MED): milestone-create.sh built the GitHub API JSON payload by
string interpolation — a title containing " or $ broke the JSON. Rebuild
with jq -n --arg so all values are safely serialised. Optional description
key is omitted when empty, preserving existing behaviour.

F-13 (LOW): pr-metadata.sh created a mktemp tmpfile inside
curl_gitea_pull() but only removed it in success paths. Add
trap 'rm -f "$body_file"' EXIT immediately after mktemp so early-exit
paths (set -e, SIGINT) also clean up.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Kt2D8TsnDwhtzEAPijsNmR

packages/mosaic/framework/tools/git/issue-assign.sh

@@ -98,27 +98,32 @@ case "$PLATFORM" in
         ;;
     gitea)
         # tea issue edit syntax
-        REPO_ARGS=$(get_gitea_repo_args) || {
-            echo "Error: Could not resolve Gitea repo/login args for remote host" >&2
+        REPO_SLUG=$(get_repo_slug) || {
+            echo "Error: Could not resolve Gitea repo slug from remote" >&2
             exit 1
         }
-        CMD="tea issue edit $ISSUE $REPO_ARGS"
+        REPO_LOGIN=$(get_gitea_login) || {
+            echo "Error: Could not resolve Gitea login for remote host" >&2
+            exit 1
+        }
+        REPO_ARGS=(--repo "$REPO_SLUG" --login "$REPO_LOGIN")
+        CMD=(tea issue edit "$ISSUE" "${REPO_ARGS[@]}")
         NEEDS_EDIT=false
 
         if [[ -n "$ASSIGNEE" ]]; then
             # tea uses --assignees flag
-            CMD="$CMD --assignees \"$ASSIGNEE\""
+            CMD+=(--assignees "$ASSIGNEE")
             NEEDS_EDIT=true
         fi
         if [[ -n "$LABELS" ]]; then
             # tea uses --labels flag (replaces existing)
-            CMD="$CMD --labels \"$LABELS\""
+            CMD+=(--labels "$LABELS")
             NEEDS_EDIT=true
         fi
         if [[ -n "$MILESTONE" ]]; then
-            MILESTONE_ID=$(tea milestones list $REPO_ARGS 2>/dev/null | grep -E "^\s*[0-9]+" | grep "$MILESTONE" | awk '{print $1}' | head -1)
+            MILESTONE_ID=$(tea milestones list "${REPO_ARGS[@]}" 2>/dev/null | grep -E "^\s*[0-9]+" | grep "$MILESTONE" | awk '{print $1}' | head -1)
             if [[ -n "$MILESTONE_ID" ]]; then
-                CMD="$CMD --milestone $MILESTONE_ID"
+                CMD+=(--milestone "$MILESTONE_ID")
                 NEEDS_EDIT=true
             else
                 echo "Warning: Could not find milestone '$MILESTONE'" >&2
@@ -126,7 +131,7 @@ case "$PLATFORM" in
         fi
 
         if [[ "$NEEDS_EDIT" == true ]]; then
-            eval "$CMD"
+            "${CMD[@]}"
             echo "Issue #$ISSUE updated successfully"
         else
             echo "No changes specified"