docs(06): complete Phase 06 — desktop wrapper + CI/CD pipeline verified

- 06-01: Tauri scaffold complete
- 06-02: Native features (tray, window-state, autostart, version check, AppImage)
- 06-03: Gitea CI/CD pipeline green (Run #89 — all 3 jobs pass)
- Clean up handoff and continue-here files
- Update STATE.md to 100% (all 6 phases complete)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.planning/HANDOFF.json

@@ -1,29 +0,0 @@
-{
-  "version": "1.0",
-  "timestamp": "2026-06-25T10:36:54.489Z",
-  "phase": "06",
-  "phase_name": "desktop-client-ci-cd",
-  "phase_dir": ".planning/phases/06-desktop-client-ci-cd",
-  "plan": 3,
-  "task": 4,
-  "total_plans": 3,
-  "completed_plans": ["06-01"],
-  "in_progress_plans": ["06-03"],
-  "remaining_plans": ["06-02"],
-  "status": "in_progress",
-  "stopped_at": "Plan 06-03 Task 4 — CI pipeline verification pending (Run #87)",
-  "resume_command": "/gsd-execute-phase 6",
-  "blockers": [],
-  "human_actions_pending": [
-    "Check CI pipeline Run #87 result at https://git.vicolab.de/schalli/tessera-ctl/actions",
-    "If pipeline still fails, check type-check step — prisma generate postinstall was added"
-  ],
-  "decisions": [
-    "Gitea user: schalli, repo: schalli/tessera-ctl (private)",
-    "Gitea URL: https://git.vicolab.de",
-    "Git remote uses embedded token credentials in URL",
-    "act_runner already existed as Docker container, reused instead of creating new",
-    "Replaced pnpm/action-setup@v4 with corepack for Gitea Actions compatibility",
-    "Added prisma generate postinstall to apps/api for CI type-check"
-  ]
-}