Fix potential crashes and unhandled exceptions in character helper functions (Batch char-11)

[Ra229287]

This PR fixes bugs #1250 to #1254.

Packet

{
  "schema": "spark-compete-hotfix-v1",
  "event": "spark-compete-first-event",
  "submission_mode": "public_repo_pr",
  "team": {
    "name": "Bug Hunters",
    "members": [
      "Ra229287",
      "Member Two",
      "Member Three"
    ],
    "llm_device_holder": "Ra229287",
    "device_holder_github": "https://github.com/Ra229287",
    "github_accounts": [
      "Ra229287"
    ]
  },
  "target_repo": {
    "id": "vibeforge1111/spark-character",
    "source": "https://github.com/vibeforge1111/spark-character",
    "owner_surface": "spark-character"
  },
  "issue": {
    "type": "bug",
    "severity": "medium",
    "title": "Potential unhandled crashes in character helper functions (Batch char-11)",
    "actual_behavior": "Various character functions crashed with raw tracebacks when variables did not conform to expected formats.",
    "expected_behavior": "All helper functions should gracefully check parameter structures and parameter types, falling back to safe defaults without tracebacks.",
    "repro_steps": [
      "Pass invalid types to _accept_rewrite_or_keep in src/spark_character/pipeline.py",
      "Pass invalid types to run_probe in src/spark_character/probes.py",
      "Pass invalid types to _parse_score in src/spark_character/probes.py",
      "Pass invalid types to scan_invisible_unicode in src/spark_character/prompt_guard.py",
      "Pass invalid types to scan_stored_prompt_injection in src/spark_character/prompt_guard.py"
    ],
    "affected_workflow": "Character pipeline life-cycle"
  },
  "evidence": {
    "safe_links_only": true,
    "before_after_proof": "Before: raw traceback crashes. After: safe type validation guards prevent all tracebacks.",
    "links": [
      "https://github.com/vibeforge1111/spark-character/pull/318"
    ],
    "forbidden": [
      "pdf",
      "zip",
      "exe",
      "unknown downloads",
      "shortened links",
      "archives",
      "binaries",
      "tokens",
      "browser cookies",
      "wallet material",
      "raw logs",
      "raw conversations",
      "raw memory",
      "raw patches",
      "private repo maps",
      "private scoring details"
    ]
  },
  "proposed_fix": {
    "approach": "Added explicit type checks, try-except containment guards, and fallback initializers across 5 character helper functions.",
    "files_expected": [
      "src/spark_character/pipeline.py",
      "src/spark_character/probes.py",
      "src/spark_character/prompt_guard.py"
    ],
    "tests_or_smoke": "Verified locally."
  },
  "pr": {
    "branch": "bug-fixes-group-13-batch-char-11",
    "title_prefix": "[spark-compete]",
    "author_github": "Ra229287",
    "body_must_include": [
      "packet",
      "team",
      "pr_author",
      "repo",
      "actual_behavior",
      "expected_behavior",
      "repro_steps",
      "before_after_proof",
      "tests_or_smoke",
      "duplicate_notes",
      "risk_notes",
      "review_claim"
    ],
    "url": "https://github.com/vibeforge1111/spark-character/pull/318"
  },
  "review_claim": {
    "risk_notes": "None",
    "duplicate_notes": "None",
    "review_state_requested": "pr_review",
    "evidence_types": [
      "before_screenshot",
      "after_screenshot",
      "smoke_test"
    ],
    "impact_claim": "medium"
  },
  "submission_target_url": "https://github.com/vibeforge1111/spark-character/pull/318"
}