docs: correct file naming convention — foundational docs are ALL-CAPS

The previous naming guide was incomplete. The actual convention is:

**Foundational docs:** ALL-CAPS
- Root entry-points: AGENTS.md, README.md (discovery paths)
- Agent instruction: .agents/OIKOS.md, .agents/HERMES.md (docs agents read first)
- Reference docs: GLOSSARY.md (like classic repo files: LICENSE, CHANGELOG)

**Content pages:** lowercase-with-dashes
- Containers: <id>-<name>.md (ID from inventory)
- Infrastructure: <topic>.md (system description)
- Plans/investigations: YYYY-MM-DD-slug.md (date-sorted)
- Section indices: README.md (conventional)

**Skills:** special pattern
- <name>/SKILL.md where <name> is lowercase-with-dashes
- SKILL.md filename is always uppercase — signpost for tools and humans

Uppercase is reserved for foundational/signpost docs; all paths otherwise use
lowercase with hyphens (no underscores).

Updated page-templates.md with expanded explanation, and updated AGENTS.md +
README.md to reference the corrected convention.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -64,7 +64,7 @@ Resolved cases move to [`investigations/archive/`](knowledge/sources/investigati
 
 ## Conventions
 
-- **File naming.** Root entry-points are ALL-CAPS; containers use `<id>-<name>.md`; infrastructure pages use lowercase-with-dashes; plans and incident records use `YYYY-MM-DD-slug.md`. See [page-templates.md](.agents/shared/page-templates.md) for the full rules.
+- **File naming.** Foundational docs (entry-points, agent instruction, references) are ALL-CAPS (`AGENTS.md`, `OIKOS.md`, `GLOSSARY.md`); containers use `<id>-<name>.md`; infrastructure pages use lowercase-with-dashes; plans and incidents use `YYYY-MM-DD-slug.md`; skills are `<name>/SKILL.md`. See [page-templates.md](.agents/shared/page-templates.md) for the full rules.
 - **Each node page** ends with a `## Changelog` section. Reverse-chronological. Entry format:
   ```
   ### YYYY-MM-DD — short title