v1.13.15-agentlint: instruction-file audit against AgentLint 31-check standard

Manual audit pass against 0xmariowu/AgentLint's evidence-backed checks
(MIT, drawn from 265 versions of Anthropic's internal Claude Code
system prompt).

Findings and fixes:
- Identity sections ("You are the assistant running inside ...") removed
  from BOOCHAT.md (line 3) and BOOCODER.md (line 5). The model already
  knows where it's running; the openers were emphatic decoration.
- CLAUDE.local.md added to .gitignore (.env was already covered).
  Claude Code's Glob tool ignores .gitignore by default, which means
  any local override file was otherwise readable by any agent walking
  the workspace.
- CLAUDE.md unchanged — already passes all 10 checks. Emphasis density
  0.58/1000 words (under Anthropic's 1.4/1000 endpoint); two IMPORTANT/
  MUST references are load-bearing (tsc-noEmit footgun, v1.13.7
  includeUsage invariant); zero identity sections; zero --no-verify
  references; 27,682 chars (under the 40,000-char silent-drop limit).
  Line count (153) is over the 60-120 target band, but the brief
  explicitly forbids structural rewrites in the audit pass.

Targets not in scope:
- /opt/boocode/AGENTS.md does not exist in this repo (removed in v1.12,
  per CLAUDE.md:152). The global agent registry lives at /data/AGENTS.md
  (bind-mounted from outside the repo); can't be touched by this batch.
- No .github/workflows/ directory — SHA-pin audit (step 8) skipped.

Cumulative effect: model spends fewer tokens parsing instruction-file
ceremony in BOOCHAT/BOOCODER and receives sharper priority signal per
Anthropic's measured-evolution data. Zero code changes.

.gitignore

@@ -1,6 +1,7 @@
 node_modules
 dist
 .env
+CLAUDE.local.md
 *.log
 .DS_Store
 .vite

BOOCHAT.md

@@ -1,7 +1,5 @@
 # BooChat
 
-You are the assistant running inside BooChat — a self-hosted developer chat app.
-
 ## Capabilities
 
 - Read-only file tools: `view_file`, `list_dir`, `grep`, `find_files`

BOOCODER.md

@@ -2,8 +2,6 @@
 
 > (Stub. v2.0 implementation pending. This file documents the intended contract.)
 
-You are the assistant running inside BooCoder — the write-capable companion to BooChat.
-
 ## Capabilities
 
 - Everything in `BOOCHAT.md`