passepartout: v0.5.0 File Reorganization

Extract non-core fragments using self-repair criterion:
- core-context -> symbolic-awareness (224 lines, fboundp guards in think())
- heartbeat generation -> symbolic-events (renamed events-start-heartbeat)

Rename 23 files for clarity and new naming scheme:
- 6 core: core-package, core-transport, core-pipeline,
          core-perceive, core-reason, core-act
- 13 system: symbolic-*, neuro-*, embedding-*, channel-shell
- 4 gateway: channel-cli, channel-tui-*, channel-tui-state

Utility relocations:
- markdown-strip -> programming-markdown
- plist-keywords-normalize -> programming-lisp
- cognitive-tool-prompt -> programming-tools
- VAULT-MEMORY -> security-vault
- Merge *backend-registry* into *probabilistic-backends*

Split gateway-messaging into channel-telegram/channel-signal/
channel-discord/channel-slack (4 independent skills)

Delete dead system-model.lisp (16-line wrapper)

Document self-repair criterion in DESIGN_DECISIONS

Version bump: 0.4.3 -> 0.5.0

README.org

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