Implement Sophia MVP stages 4-7 (introspection, queries, persistence, polish)

Brings the system from "engrams cluster + form synapses" to a complete
end-to-end demo: ingest text, watch it cluster, ask questions, restart
with state intact.

- Stage 4: birth introspection (taxonomy/goals/open_questions via LLM,
  bounded by the global parallel-op semaphore), per-engram memory log,
  click-to-inspect side panel.
- Stage 5: queries as conversations. POST /api/galaxy/:id/query embeds
  the question, materializes a pinned Query-Engram at the donut center,
  runs broadcast retrieval (global cosine scan + 1-hop synaptic
  expansion with attenuation) and fans out responder LLM calls. The
  integrator runs every 2s on accumulated snippets and streams the
  refining answer back over SSE; responders briefly transition to
  Conversing on the WS bus so the right dots light up.
- Stage 6: snapshot persistence. sled-backed store keyed by galaxy id,
  JSON-encoded values (bincode chokes on internally-tagged enums like
  Manifest/MemoryKind), 60s periodic snapshot task, hydrate-on-boot,
  DELETE /api/galaxy/:id wired through. State survives kill -9.
- Stage 7: HUD additions (sim ticks/sec, LLM queue depth, FPS) via a
  new GET /api/stats polled at 1Hz. `sophia demo` subcommand boots the
  server then auto-ingests a 50-paragraph corpus baked into the binary
  with include_str!. README quickstart added.

Token caps for query_responder/integrator bumped (gemma-4-e4b is a
thinking model — output budget must cover hidden reasoning + visible
answer, otherwise content comes back empty). Pinned engrams skip
physics; their tick scheduling is also skipped at materialization so
they stay perfectly still at the donut center.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

assets/demo_corpus.txt

@@ -0,0 +1,50 @@
+Pasta carbonara uses guanciale, eggs, pecorino romano, and freshly cracked black pepper.
+Spaghetti aglio e olio combines garlic, olive oil, chili flakes, and parsley over al dente pasta.
+Risotto requires arborio rice, slowly added warm broth, and constant stirring to release starch.
+Pesto alla genovese blends basil, pine nuts, garlic, parmesan, pecorino, and olive oil.
+Cacio e pepe is just pasta, pecorino, and pepper — emulsion comes from starchy pasta water.
+Lasagne bolognese layers ragu, bechamel, and pasta sheets between melted parmesan.
+Amatriciana sauces guanciale and tomato together with a touch of pecorino.
+Gnocchi alla romana use semolina baked with butter and cheese instead of potato.
+Tiramisu layers savoiardi soaked in espresso with mascarpone whipped with eggs and sugar.
+Sourdough bread relies on a wild yeast starter and slow bulk fermentation for flavor.
+Bechamel sauce is built from a roux of butter and flour cooked into milk.
+Caramelization happens to sugars above 160 C; the Maillard reaction needs proteins and amines.
+Sushi rice is seasoned with vinegar, sugar, and salt while still warm so seasoning soaks evenly.
+Korean kimchi ferments napa cabbage with chili paste, garlic, ginger, and salted shrimp.
+French croissants get their flake from laminated layers of cold butter folded into yeasted dough.
+Backpropagation computes gradients of a loss with respect to neural network weights via the chain rule.
+Gradient descent updates model parameters in the direction that reduces the loss the most.
+Stochastic gradient descent samples mini-batches so each step costs less and adds useful noise.
+Adam adapts a per-parameter learning rate using running moments of the gradients.
+Convolutional neural networks share weights across spatial locations to exploit translation invariance.
+Recurrent networks process sequences by feeding state from one step into the next.
+Transformers attend over a whole sequence at once instead of recurring through it.
+Self-attention computes a weighted sum of values where weights are softmax of query-key dot products.
+Layer normalization stabilizes training by normalizing activations along the feature dimension.
+Dropout randomly zeroes activations during training as a regularizer.
+Residual connections let very deep networks train by giving gradients an additive path back.
+Word embeddings map discrete tokens to dense vectors learned end-to-end with the task.
+A loss function turns predictions and targets into a single scalar to minimize.
+Cross-entropy loss compares a predicted distribution to a one-hot target.
+Reinforcement learning learns a policy by trial-and-error rewards in an environment.
+Markov decision processes describe RL with states, actions, transitions, and rewards.
+Q-learning estimates the value of taking each action in each state.
+Policy gradient methods directly adjust the policy to maximize expected reward.
+The Roman Empire fell in 476 CE when Romulus Augustulus, the last western emperor, was deposed.
+Constantinople fell to the Ottomans under Mehmed II in 1453, ending the Byzantine Empire.
+The Magna Carta of 1215 limited the power of the English monarchy and protected baronial rights.
+The printing press, perfected by Gutenberg around 1440, accelerated the spread of literacy in Europe.
+The Treaty of Westphalia in 1648 ended the Thirty Years War and established sovereign-state diplomacy.
+The French Revolution began in 1789 with the storming of the Bastille on July 14.
+The Industrial Revolution started in late-eighteenth-century Britain with mechanized textile production.
+The American Civil War ran from 1861 to 1865 over slavery, states' rights, and union.
+World War I lasted from 1914 to 1918 and was triggered by the assassination of Archduke Franz Ferdinand.
+The Russian Revolution of 1917 replaced the tsarist autocracy with Bolshevik rule.
+The Great Depression began with the 1929 Wall Street Crash and lasted through the 1930s.
+World War II ended in 1945 after Germany surrendered in May and Japan in September.
+The United Nations was founded in 1945 in San Francisco to prevent another global war.
+The Cold War divided the world between US and Soviet spheres from roughly 1947 to 1991.
+The Berlin Wall fell on November 9, 1989, symbolizing the end of the Cold War in Europe.
+The Apollo 11 mission landed humans on the Moon for the first time on July 20, 1969.
+The European Union was established by the Maastricht Treaty in 1993, succeeding the EEC.