Consolidate poc-memory and poc-agent configs

poc-memory now reads from poc-agent's config.json5 as the primary
config source. Memory-specific settings live in a "memory" section;
API credentials are resolved from the shared model/backend config
instead of being duplicated.

- Add "memory" section to ~/.config/poc-agent/config.json5
- poc-memory config.rs: try shared config first, fall back to
  legacy JSONL
- API fields (base_url, api_key, model) resolved via
  memory.agent_model -> models -> backend lookup
- Add json5 dependency for proper JSON5 parsing
- Update provisioning scripts: hermes -> qwen3_coder tool parser

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -2643,6 +2643,7 @@ dependencies = [
  "crossterm 0.28.1",
  "faer",
  "jobkit",
+ "json5",
  "libc",
  "log",
  "memmap2",