fix(ui): prevent resume upload rerun loop, show start button on all steps

Resume upload caused infinite st.rerun() because the file_uploader
retains files across reruns. Added `not has_resume` guard. Moved the
Start button from step-7-only to the sidebar so it's always accessible.

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

ui.py

@@ -943,7 +943,7 @@ if show_config:
                 label_visibility="collapsed",
                 help="Supported format: PDF. Max size: 10MB.",
             )
-            if resume_file:
+            if resume_file and not has_resume:
                 os.makedirs("data/resume", exist_ok=True)
                 with open("data/resume/resume.pdf", "wb") as f:
                     f.write(resume_file.read())
@@ -1240,23 +1240,6 @@ Or run `python connect_google.py` for OAuth-based setup.
                 if st.button(f"Next →", use_container_width=True, type="primary", key="nav_next"):
                     st.session_state.setup_step = current_step + 1
                     st.rerun()
-            else:
-                # Last step — show launch button
-                can_start = has_resume and bool(roles) and bool(locations) and bool(ever_jobs_platforms)
-                start = st.button(
-                    "🚀 Launch Search",
-                    disabled=st.session_state.running or not can_start,
-                    use_container_width=True,
-                    type="primary",
-                    key="start_btn",
-                )
-                if not can_start:
-                    missing = []
-                    if not has_resume: missing.append("resume")
-                    if not roles: missing.append("roles")
-                    if not locations: missing.append("locations")
-                    if not ever_jobs_platforms: missing.append("platforms")
-                    st.caption(f"Missing: {', '.join(missing)}")
 
     # ────────────────────────────────────────────────────────────────────
     # RIGHT SIDEBAR — Run Readiness Panel
@@ -1330,6 +1313,24 @@ Or run `python connect_google.py` for OAuth-based setup.
   <div class="badge-row">{badges_html}</div>
 </div>""")
 
+        # Start Search CTA — always visible in sidebar
+        st.markdown("---")
+        can_start = has_resume and bool(roles) and bool(locations) and bool(ever_jobs_platforms)
+        start = st.button(
+            "🚀 Start AI Job Search" if not st.session_state.running else "⏳ Running…",
+            disabled=st.session_state.running or not can_start,
+            use_container_width=True,
+            type="primary",
+            key="start_btn",
+        )
+        if not can_start:
+            missing = []
+            if not has_resume: missing.append("resume")
+            if not roles: missing.append("roles")
+            if not locations: missing.append("locations")
+            if not ever_jobs_platforms: missing.append("platforms")
+            st.caption(f"Missing: {', '.join(missing)}")
+
 else:
     roles = st.session_state.get("_last_roles", _cfg("_cfg_roles"))
     locations = st.session_state.get("_last_locations", _cfg("_cfg_locations"))