fix(tempo): fix EU base URL, trailing space in account ID, and tempo_synced tracking

Root causes found for Tempo worklogs never reaching Tempo:
1. Wrong API region: workspace is on api.eu.tempo.io/4 but code used api.tempo.io/4
   → Tempo returned "User is invalid" (400) for all POST /worklogs
2. Trailing space in jira_account_id stored in DB (now stripped with .strip())
3. tempo_synced field was never updated even on success (now set from Tempo response)

Fix: add tempo.base_url system_config key (admin-configurable without redeploy),
fall back to TEMPO_BASE_URL env-var, then global default. DB already updated with
https://api.eu.tempo.io/4 for this workspace.

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

backend/app/config.py

@@ -63,6 +63,9 @@ class Settings(BaseSettings):
     TEMPO_API_TOKEN: str = ""
     TEMPO_API_VERSION: int = 4
     TEMPO_DEFAULT_WORK_TYPE: str = "Red Team"
+    # Tempo API base URL — use https://api.eu.tempo.io/4 for EU workspaces.
+    # Can also be set via system_configs key "tempo.base_url" at runtime.
+    TEMPO_BASE_URL: str = ""  # empty → falls back to https://api.tempo.io/4
 
     # ── OSINT / Intelligence ────────────────────────────────────────
     NVD_API_KEY: str = ""  # optional; increases NVD rate limit from 5/30s to 50/30s