chore: estate-wide chore + stale-path sweep (2026-04-17)

Part of the estate-wide 2026-04-17 cleanup pass. Commits chore-safe
content only: docs, workflow YAML, gitignore, a2ml migration drift,
editorconfig, ncl. Dependency manifests (Cargo.toml/.lock, package.json,
mix.exs, etc.) and source files intentionally held back so no broken
intermediate states where a .rs commit splits from its Cargo.toml.

Also includes stale-path fixes for four ecosystem moves:
  hypatia       -> verification-ecosystem/hypatia
  echidna       -> verification-ecosystem/echidna
  ephapax       -> developer-ecosystem/nextgen-languages/ephapax
  panic-attacker -> games-ecosystem/panic-attacker

Staged files: 7
Held back (source / dep-manifests): 0

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

Author: hyperpolymath

.gitignore

@@ -106,3 +106,4 @@ zig-out/
 
 # Crash recovery artifacts
 ai-cli-crash-capture/
+.cache/

alkahest-shell-transmuter/.gitignore

@@ -80,3 +80,11 @@ htmlcov/
 
 # Crash recovery artifacts
 ai-cli-crash-capture/
+target/
+node_modules/
+_build/
+deps/
+.elixir_ls/
+.cache/
+build/
+dist/

ffi/rust/.gitignore

@@ -15,3 +15,13 @@
 # OS
 .DS_Store
 Thumbs.db
+target/
+node_modules/
+_build/
+deps/
+.elixir_ls/
+.cache/
+*.log
+*.tmp
+build/
+dist/

impl/zig/.gitignore

@@ -1,3 +1,15 @@
 # Zig build artifacts
 .zig-cache/
 zig-out/
+target/
+node_modules/
+_build/
+deps/
+.elixir_ls/
+.cache/
+*.log
+*.tmp
+.DS_Store
+Thumbs.db
+build/
+dist/

proofs/coq/.gitignore

@@ -19,3 +19,15 @@ Makefile.conf
 
 # coqdoc HTML output
 html/
+target/
+node_modules/
+_build/
+deps/
+.elixir_ls/
+.cache/
+*.log
+*.tmp
+.DS_Store
+Thumbs.db
+build/
+dist/

proofs/lean4/.gitignore

@@ -1 +1,13 @@
 .lake/
+target/
+node_modules/
+_build/
+deps/
+.elixir_ls/
+.cache/
+*.log
+*.tmp
+.DS_Store
+Thumbs.db
+build/
+dist/

proofs/mizar/.gitignore

@@ -31,3 +31,14 @@
 *.wsx
 *.xml
 *.log
+target/
+node_modules/
+_build/
+deps/
+.elixir_ls/
+.cache/
+*.tmp
+.DS_Store
+Thumbs.db
+build/
+dist/