docs(kyberforge): fix provenance chain gap in agent-primitive-schema.md

The file's body cites APM's Python source directly (apm_cli/models/validation.py,
apm_cli/primitives/models.py) to support its "no dedicated Agent validation"
claim, but source_keys only listed context7-microsoft-apm — the apm-github-repo
source_key was missing, and sources.md's apm-github-repo entry didn't list this
file under Contributing files either. The three sibling schema files from the
same commit (prompt/instructions/hooks) all cited both sources correctly.

Found via post-implementation review of issue #89.

plugins/kyberforge/docs/research/docs/microsoft-apm/agent-primitive-schema.md

@@ -2,6 +2,7 @@
 topic: agent-primitive-schema
 source_keys:
   - context7-microsoft-apm
+  - apm-github-repo
 ---
 
 ## Agent frontmatter is not a fixed APM-defined schema

plugins/kyberforge/docs/research/docs/microsoft-apm/sources.md

@@ -11,5 +11,5 @@
 
 - **URL:** https://github.com/microsoft/apm
 - **Description:** APM's own Python source (`src/apm_cli/`) read directly for schema/compile-mapping ground truth where Context7's doc snippets were thin — specifically `primitives/models.py` and `primitives/discovery.py` (primitive dataclasses and discovery globs), `integration/prompt_integrator.py`, `integration/command_integrator.py`, `integration/instruction_integrator.py`, `integration/hook_integrator.py`, `integration/hook_native_formats.py`, `integration/hook_ir.py`, `integration/_hook_dropped_targets.py`, `integration/targets.py` (`KNOWN_TARGETS`/`PrimitiveMapping` per-target deploy config), `compilation/claude_formatter.py` and `compilation/distributed_compiler.py` (instruction fold-in to CLAUDE.md/AGENTS.md), and `models/validation.py`.
-- **Contributing files:** prompt-primitive-schema.md, instructions-primitive-schema.md, hooks-primitive-schema.md
+- **Contributing files:** agent-primitive-schema.md, prompt-primitive-schema.md, instructions-primitive-schema.md, hooks-primitive-schema.md
 - **Status:** `extracted`