Phase 0: scaffold tree + manifest

- README, .gitignore, CLAUDE.md (project conventions)
- docs/PHASE0.md — full Phase 0 manifest (locked substrate)
- 10 root .lua modules + 4 ffi/ bindings, all stubs raising NotImplemented
  with module-scoped responsibilities matching the manifest
- config.lua wired to current dirac/hossenfelder endpoints (qwen-coder-7b
  snappy/32k + cloud via OpenRouter through hossenfelder)

File names match docs/PHASE0.md §4 exactly. Module bodies fill in across
later phases; the tree shape is locked.

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

main.lua

@@ -0,0 +1,32 @@
+-- main.lua — entry point
+-- Phase 0: arg parsing, config load, REPL start.
+-- See docs/PHASE0.md §4, §10.
+
+local function load_config()
+    -- Resolution order per PHASE0.md §10:
+    --   1. --config <path>   2. $AISH_CONFIG
+    --   3. ~/.config/aish/config.lua   4. ./config.lua
+    -- Phase 0 stub: pick the first existing path; no CLI parsing yet.
+    local home = os.getenv("HOME") or ""
+    local candidates = {
+        os.getenv("AISH_CONFIG"),
+        home .. "/.config/aish/config.lua",
+        "./config.lua",
+    }
+    for _, path in ipairs(candidates) do
+        if path then
+            local f = io.open(path, "r")
+            if f then f:close(); return dofile(path), path end
+        end
+    end
+    error("aish: no config.lua found in any standard location")
+end
+
+local function main()
+    local config, config_path = load_config()
+    io.stderr:write(("aish: loaded config from %s\n"):format(config_path))
+    local repl = require("repl")
+    repl.run(config)
+end
+
+main()