Fold SPEC/maven/ROADMAP into DESIGN.md and drop the stale session logs

15 root markdown files, ~4,900 lines against ~33,000 lines of Go, with at least
three pairs contradicting each other. When five documents describe the
architecture, the code becomes the only trustworthy one — which defeats the
point of having them. That drift is why the resident-model question had four
incompatible answers.

SPEC.md, maven.md and ROADMAP.md are deduped into DESIGN.md rather than
concatenated, with a "Superseded" section carrying eight retired decisions and
what replaced each: classifier-owns-the-route (the cascade is still the live
path, but as a stopgap, not a design to extend), faster-whisper/vosk/silero,
the small-model phrasing claim, sqlcipher, the Kotlin/Spring sketches,
obsidian->chroma, script deployment, and FloorEnrollment. Superseded material
is kept and marked rather than deleted, so it cannot read as current.

SESSION-05/06-07-2026.md and PLANS.md are removed outright — git history holds
them, and both were verified tracked before deletion.

Go doc comments citing the deleted files are repointed to the equivalent
DESIGN.md sections. Several asserted designs that were already retired, so the
claims are corrected and not just relinked: stt.go named faster-whisper as
production (it is whisper.cpp), tts.go named silero (it is piper), intent.go
still described the classifier as owning the route, and stale vosk/chroma
vocabulary is replaced. ECOSYSTEM-SPEC.md references are deliberately
untouched — that is a different document, and a naive grep for SPEC.md matches
it.

Root markdown drops from 4,880 to ~3,700 lines. The review's ~1,500 target is
not reachable while keeping the files it also said to keep — those alone are
2,553 lines — so trimming further needs a separate decision on
MAVEN_ECOSYSTEM_ARCHITECTURE.md and PROGRESS.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01X5JApcrCRVGmqrxnhynSik

internal/tts/tts.go

@@ -5,12 +5,12 @@
 // PCM, headerless per the audio package; the voice sink + reference client
 // wrap it in a WAV at the disk edge.
 //
-// Per spec (maven.md § stt/tts): silero (ru-native) is the production tts,
-// piper (ru) is the safe floor. Both are CPU-only on the ryzen box; both
-// ship as separate worker module processes (cmd/mavttsd today with the
-// Stub handler; production swaps in onnxruntime / espeak-ng in the same
-// main, no tts-package change). The daemon wires one — Remote pointing at
-// the worker socket if configured, Stub otherwise.
+// Per DESIGN.md § Voice pipeline (STT / TTS): piper is the production tts
+// (subprocess + espeak-ng, CPU-only on the ryzen box, driven by cmd/mavttsd);
+// the older silero pick is retired (DESIGN.md § Superseded, "named STT/TTS
+// model picks"). A different voice is a model-file swap, not a code change.
+// The daemon wires one impl — Remote pointing at the worker socket if
+// configured, Stub otherwise.
 //
 // The Stub returns a short deterministic tone (a 200ms mid-frequency sine
 // burst) so the voice loop round-trips end-to-end without a model. The