fix(bmm): unwrap case-file template, tighten PRD discovery glob

Two PR review fixes:

- Strip the surrounding markdown code fence from case-file-template.md
  so initializing a case file doesn't nest the whole artifact inside a
  code block. The template is now the structure directly, with usage
  notes in an HTML comment that doesn't render. Matches the BMM idiom
  used by bmad-create-story/template.md.
- Drop the stale `*-archaeology.md` reference from bmad-create-prd
  step-01 discovery. The single-procedure restructure removed
  archaeology as a distinct mode, so case files only carry the
  `*-investigation.md` suffix. Tighten the glob accordingly.

src/bmm-skills/2-plan-workflows/bmad-create-prd/steps-c/step-01-init.md

@@ -87,7 +87,7 @@ Try to discover the following:
 - Research Documents (`/*research*.md`)
 - Project Documentation (generally multiple documents might be found for this in the `{project_knowledge}` or `docs` folder.)
 - Project Context (`**/project-context.md`)
-- Investigation Files (`{implementation_artifacts}/investigations/*.md`) — `bmad-investigate` case files when the PRD is being driven by a forensic investigation rather than greenfield ideation. Captures both `*-investigation.md` and `*-archaeology.md`.
+- Investigation Files (`{implementation_artifacts}/investigations/*-investigation.md`) — `bmad-investigate` case files when the PRD is being driven by a forensic investigation rather than greenfield ideation.
 
 <critical>Confirm what you have found with the user, along with asking if the user wants to provide anything else. Only after this confirmation will you proceed to follow the loading rules</critical>
 

src/bmm-skills/4-implementation/bmad-investigate/case-file-template.md

@@ -1,12 +1,7 @@
-# Case File Template
+<!-- Case file template. Copy this structure into a new case file at the start of an investigation.
+     Update sections as evidence accumulates. Never delete a hypothesis: update its Status and add a Resolution.
+     Append follow-up sessions under dated `## Follow-up: {date}` blocks instead of overwriting earlier reasoning. -->
 
-The output file uses the structure below. Initialize it once at the start of the case, then update sections as evidence
-accumulates. Never delete a hypothesis. Update its Status and add a Resolution. Append follow-up sessions under dated
-`## Follow-up: {date}` blocks instead of overwriting earlier reasoning.
-
----
-
-```markdown
 # Investigation: {title}
 
 ## Case Info
@@ -161,4 +156,3 @@ overwrite earlier blocks.
 ### Updated Conclusion
 
 {Revised assessment incorporating new evidence.}
-```