docs: rename self-references from "LLM Wiki" to "memex"

Replace project self-references throughout README, SETUP, and the example
CLAUDE.md files. External artifact titles are preserved as-is since they
refer to the actual title of the Claude design artifact.

Also add a "Why 'memex'?" aside to the README that roots the project in
Vannevar Bush's 1945 "As We May Think" essay, where the term originates.
The compounding knowledge wiki is the LLM-era realization of Bush's
memex concept: the "associative trails" he imagined are the related:
frontmatter fields and wikilinks the agent maintains.

Kept lowercase where referring to the generic pattern (e.g. "an LLM wiki
persists its mistakes") since that refers to the class of system, not
this specific project.

docs/examples/global-CLAUDE.md

@@ -1,9 +1,9 @@
-# Global Claude Code Instructions — Wiki Section
+# Global Claude Code Instructions — memex Section
 
 **What this is**: Content to add to your global `~/.claude/CLAUDE.md`
 (the user-level instructions Claude Code reads at the start of every
 session, regardless of which project you're in). These instructions tell
-Claude how to consult the wiki from outside the wiki directory.
+Claude how to consult memex from outside the wiki directory.
 
 **Where to paste it**: Append these sections to `~/.claude/CLAUDE.md`.
 Don't overwrite the whole file — this is additive.
@@ -20,7 +20,7 @@ At the start of each session, read `~/projects/wiki/context/wake-up.md`
 for a briefing on active projects, recent decisions, and current
 concerns. This provides conversation continuity across sessions.
 
-## LLM Wiki — When to Consult It
+## memex — When to Consult It
 
 **Before creating API endpoints, Docker configs, CI pipelines, or making
 architectural decisions**, check the wiki at `~/projects/wiki/` for
@@ -49,7 +49,7 @@ Human-initiated wiki writes go directly to the live wiki with
 `origin: manual`. Script-initiated writes go through `staging/` first.
 See the wiki's own `CLAUDE.md` for the full ingest protocol.
 
-## LLM Wiki — How to Search It
+## memex — How to Search It
 
 Use the `qmd` CLI for fast, structured search. DO NOT read `index.md`
 for large queries — it's only for full-catalog browsing. DO NOT grep the
@@ -123,7 +123,7 @@ Rarely needed, but for "find everything on this topic across time":
 qmd search "topic" -c wiki -c wiki-archive -c wiki-conversations --json -n 10
 ```
 
-## LLM Wiki — Rules When Citing
+## memex — Rules When Citing
 
 1. **Always use `--json`** for structured qmd output. Never try to parse
    prose.
@@ -138,7 +138,7 @@ qmd search "topic" -c wiki -c wiki-archive -c wiki-conversations --json -n 10
 6. **Prefer semantic search for conceptual queries**, keyword search for
    specific names/terms.
 
-## LLM Wiki — Quick Reference
+## memex — Quick Reference
 
 - `~/projects/wiki/CLAUDE.md` — Full wiki schema and operations (read this when working IN the wiki)
 - `~/projects/wiki/index.md` — Content catalog (browse the full wiki)