fix(test): remove skip guard and soft assertions from scientific paper E2E test

- Remove Require OpenAI Key skip guard that silently skipped the suite
- Replace Run Keyword And Return Status soft RC check with direct assertion
- Convert conditional LaTeX presence check to hard assertions
- Convert conditional latex_source context field check to hard assertion
- Remove dead stderr checks (stderr redirected to stdout via stderr=STDOUT)

robot/scientific_paper_e2e_test.robot

@@ -25,7 +25,6 @@ Scientific Paper Writer Full Workflow
     Log    Testing intro stage...
     ${result}=    Run Paper Command    Hello
     Should Contain    ${result.stdout}    Paper Writer
-    Should Not Contain    ${result.stderr}    Error
 
     # Test 2: Advance to discovery
     Log    Advancing to discovery stage...
@@ -59,7 +58,6 @@ Scientific Paper Writer Full Workflow
     # Test 6: Test brainstorming stage
     Log    Testing brainstorming stage...
     ${result}=    Run Paper Command    I want to write about the impact of machine learning on healthcare, focusing on diagnostic imaging and patient outcomes    timeout=90s
-    Should Not Contain    ${result.stderr}    Error
     Length Should Be Greater Than    ${result.stdout}    50
 
     # Test 7: Verify stage may have advanced (brainstorming stage might auto-advance after LLM response)
@@ -68,10 +66,7 @@ Scientific Paper Writer Full Workflow
     # Test 8: Advance toward later stages (using structure or latex_generation as targets)
     Log    Advancing toward later stages...
     ${result}=    Run Paper Command    !next structure    timeout=120s
-    # Note: May fail if required context isn't set, which is acceptable for this E2E test
-    # The important thing is the command doesn't crash
-    ${rc_ok}=    Run Keyword And Return Status    Should Be Equal As Integers    ${result.rc}    0
-    # Note: Stage may auto-advance; exact stage verification removed
+    Should Be Equal As Integers    ${result.rc}    0
 
     # Test 9: Verify stage list command works
     Log    Verifying stage list command...
@@ -127,24 +122,17 @@ Scientific Paper Writer LaTeX Generation
     ...    stderr=STDOUT
     ...    timeout=180s
     Should Be Equal As Integers    ${result.rc}    0
-    Should Not Contain    ${result.stderr}    Error
-    Should Not Contain    ${result.stderr}    timed out
     # System should produce SOME output (not just echo the input)
     Should Not Be Equal    ${result.stdout}    Generate the complete LaTeX document
 
-    # Verify LaTeX structure (if LaTeX was generated)
+    # Verify LaTeX structure
     Log    Verifying LaTeX document structure...
-    ${has_latex}=    Run Keyword And Return Status    Should Contain    ${result.stdout}    \\documentclass
-    IF    ${has_latex}
-        Should Contain    ${result.stdout}    \\begin{document}
-        Should Contain    ${result.stdout}    \\end{document}
-        Should Contain    ${result.stdout}    \\section
-        Log    LaTeX document was generated successfully
-    ELSE
-        Log    LaTeX generation may require manual stage management or different prompting
-    END
+    Should Contain    ${result.stdout}    \\documentclass
+    Should Contain    ${result.stdout}    \\begin{document}
+    Should Contain    ${result.stdout}    \\end{document}
+    Should Contain    ${result.stdout}    \\section
 
-    # Verify context was updated (may or may not have latex_source depending on stage behavior)
+    # Verify context was updated
     Log    Verifying context is accessible...
     ${result}=    Run Process    ${PYTHON}    -m    cleveragents    actor    run
     ...    -c    ${CONFIG_FILE}
@@ -155,12 +143,7 @@ Scientific Paper Writer LaTeX Generation
     ...    -p    !context
     ...    stderr=STDOUT
     ...    timeout=30s
-    ${has_latex_context}=    Run Keyword And Return Status    Should Contain    ${result.stdout}    latex_source
-    IF    ${has_latex_context}
-        Log    Context includes latex_source field
-    ELSE
-        Log    Context does not include latex_source (may require different stage setup)
-    END
+    Should Contain    ${result.stdout}    latex_source
 
     Log    LaTeX generation test completed
 
@@ -235,7 +218,6 @@ Scientific Paper Writer Stage Navigation
 
 *** Keywords ***
 Setup Test Environment
-    Require OpenAI Key
     ${timestamp}=    Get Time    epoch
     Set Suite Variable    ${TEST_ID}    ${timestamp}
     Set Suite Variable    ${CONTEXT_NAME}    paper_e2e_${TEST_ID}
@@ -277,6 +259,3 @@ Length Should Be Greater Than
     ${length}=    Get Length    ${text}
     Should Be True    ${length} > ${min_length}    Text length ${length} is not greater than ${min_length}
 
-Require OpenAI Key
-    ${api_key}=    Get Environment Variable    OPENAI_API_KEY    default=
-    Run Keyword If    '${api_key}' == ''    Skip    OPENAI_API_KEY not set; skipping LLM integration tests