Reorganize brain: projects/ top level, rename filenames, update homepage

- Moved everything from ideas/passepartout/ to projects/passepartout/
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- Created missing _index.org files for all subdirectories
- Stripped redundant passepartout- prefix from filenames
- Rewrote root _index.org as generalized brain index (projects + concepts)
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- Deleted stale ideas/passepartout-economics.md orphan

projects/passepartout/biology-parallels.org

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+:PROPERTIES:
+:CREATED:  [2026-05-24 Sun]
+:ID:       2afd9a3c-e96a-54c7-ac77-a05a28065b4b
+:END:
+#+title: Biology as Proof of the Lisp Model
+#+filetags: :passepartout:biology:lisp:parallels:evolution:
+
+Striking parallels between microbiology and the Lisp model:
+
+1. **Homoiconicity** — DNA is code and data in the same molecule; no separate source and binary
+2. **Hot-reloadable image** — alternative splicing, epigenetic marks, post-translational modifications change the running program without restart
+3. **Automatic memory management** — proteasomes degrade misfolded proteins, autophagy recycles organelles; the cell never calls free()
+4. **Interpreted dynamic language** — DNA → RNA → ribosome (interpreter) → protein; no static compilation step
+5. **Self-modifying source** — CRISPR, transposons, DNA repair modify the genome at runtime; eval on the genome
+6. **Duck typing** — protein folding depends on chemical environment, not type declarations
+7. **Concurrent real-time GC** — apoptosis breaks down cell components for recycling by neighboring cells
+
+Biology chose the Lisp model because it is more robust, adaptable, and evolvable. Evolution optimized for survival in an unpredictable environment, not peak single-thread throughput. Biology is the proof that the Lisp model can be efficient at planetary scale, running on hardware that self-assembles from food. See [[id:9af13fff-9725-542b-93b1-a555bc74ad72][Lisp economics]] for how these biological parallels inform the business model.