feat: backport config-driven run scoping and report filtering

Cherry-pick of upstream Shannon PR #326. Adds vuln_classes subset
selection, exploit toggle, code_path avoid enforcement via SDK deny
rules, deterministic findings rendering when exploit is disabled,
report filtering (min_severity, min_confidence, guidance), and
rules_of_engagement config field.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/worker/prompts/shared/_code-path-rules.txt

@@ -0,0 +1,13 @@
+<code_path_rules>
+Source-code routing. Each rule is tagged `[FILE]` (literal path) or `[GLOB]` (pattern). All paths are repository-relative.
+
+How to apply (focus rules):
+- For `[FILE]` entries — delegate analysis to the Task tool.
+- For `[GLOB]` entries — invoke the Glob tool to enumerate matches, then delegate analysis of every match to the Task tool.
+
+Avoid — out of scope. Skip entirely; the tool layer will block any access attempts.
+{{CODE_RULES_AVOID}}
+
+Focus — priority work assignments. Analyze every entry.
+{{CODE_RULES_FOCUS}}
+</code_path_rules>