docs: setup files and the client, shared and CI docs describe what is (#6277)

.dockerignore, .gitignore, deploy/initdb, ci-requirements.md,
client/README.md, shared/README.md and two web/scripts test names: dates,
issue/rule/spike ids and the stories behind each exclusion removed.

Corrected:
- client/README.md: the dev lane bundles its own APK; :main no longer
  exists; main bundles the recorded sidecar instead of re-deriving the
  version name. Its smoke-test step wrote a bare "v0.2.0", which the
  server rejects as a sidecar that is not JSON; it now writes the JSON
  shape, which the README documents.
- ci-requirements.md: one workflow, not four; the android lane builds no
  debug APK; main reads the recorded sidecar.
- .gitignore: CI fills client/ on every image build, not tag releases only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -12,13 +12,11 @@
 # Test binary, built with `go test -c`
 *.test
 
-# `make build` output. bin/minstrel was tracked until 2026-09-10 — an 18 MB
-# binary committed by accident, last refreshed by a commit about web test
-# mocks, and re-dirtied by every local build since.
+# `make build` output — an 18 MB binary that is never committed.
 bin/
 
-# Bundled Android APK + version sidecar (#397). Populated by CI for
-# tag releases; never committed. README in client/ explains the flow.
+# Bundled Android APK + version sidecar. Populated by CI on every image
+# build; never committed. README in client/ explains the flow.
 client/minstrel.apk
 client/minstrel.apk.version
 
@@ -44,10 +42,9 @@ go.work.sum
 docs/superpowers/
 
 # Per-machine Claude Code settings + remember-skill memory artifacts +
-# project-level Claude/AI instruction files. All operator-scoped; the
-# canonical project memory lives under ~/.claude/projects/ outside the
-# repo. CLAUDE.md/AGENTS.md/GEMINI.md stay on the operator's machine
-# only — they're tool-specific working notes, not project artifacts.
+# project-level Claude/AI instruction files. All per-machine;
+# CLAUDE.md/AGENTS.md/GEMINI.md are tool-specific working notes, not
+# project artifacts.
 .claude/
 .remember/
 CLAUDE.md