README down to what a user needs; the rest into docs/

The README had grown to 1,010 lines of user docs and design notes in one file,
and had gone stale: it still showed the old numbered menu, set up only three
providers, and listed preflight checks and a file layout that predate the last
three releases. It now carries install, first run, the full command
reference, the providers at a glance, troubleshooting and a docs index.

docs/:
- providers.md    presets, defaults, the model cache, context windows, each
                  provider (OpenRouter's cost guard and guardrail check are
                  written up for the first time), adding a provider
- live-sessions.md  what a switch does to running sessions, and repair
- design.md       why settings.json, why keys stay out of it (and the vault
                  per platform), the preflight checks as they are now
- bar-widget.md   the widget as it is now: providers from health.json, every
                  server provider's settings, the restart after an upgrade
- architecture.md the pieces, every file on disk and who writes it, the
                  contracts between them, where to change what
- development.md  running the tests, the conventions the code follows,
                  working on the widget, releasing
CONTRIBUTING.md points at it.

Also:
- The per-project session listing used awk, which the CLI avoids because it
  is missing from minimal images; it uses the script's own TSV helpers now,
  and tests/static.sh fails on any awk in the CLI.
- tests/static.sh checks every relative Markdown link and #anchor.
- A unit test pins the managed env keys between cm-json.py and
  claude-mode.ps1, which only a comment kept in step before.
- test_sessions covers the per-project listing, which nothing ran.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/cli/test_sessions.sh

@@ -2,7 +2,11 @@
 # Broken transcripts: the scan, dismissing and restoring, the age rule, repair.
 . "$(dirname "$0")/../lib.sh"
 
-proj="$CLAUDE_CONFIG_DIR/projects/-tmp-fixture"
+# The fixture project is filed under the slug of a real directory, so the
+# per-project listing (run from inside it) finds it the way Claude Code would.
+work="$SB/work"
+mkdir -p "$work"
+proj="$CLAUDE_CONFIG_DIR/projects/$(printf '%s' "$work" | sed 's|[^a-zA-Z0-9]|-|g')"
 mkdir -p "$proj"
 transcript() {   # <session-id> [age-in-hours]
     printf '%s\n' \
@@ -34,6 +38,10 @@ run_cm repair-session --all
 expect_out '2 hidden: 1 ignored, 1 older than 7 days' 'hidden sessions are always counted'
 run_cm repair-session --ignored
 expect_out 'still broken' 'the dismissed list reconciles against the disk'
+OUT="$(cd "$work" && "$CM" repair-session 2>&1 | sed "s/${ESC}\[[0-9;]*m//g")"
+expect_out 'cccc-ok' 'the per-project listing shows every transcript here'
+expect_out '(hidden: ignored)' 'and marks a dismissed one'
+expect_out '(hidden: older than 7 days)' 'and an age-hidden one'
 run_cm repair-session --ignore zzzz
 expect_rc 1 'an unknown session cannot be dismissed'
 run_cm repair-session --unignore aaaa-new