docs: consolidate doc/ into docs/

One documentation root: the prose docs (building-and-deps, self-hosting
architecture/compiler, tools-deps, grammar.ebnf) join the spec and RFCs under
docs/. References in README and deps-conformance-test updated.

docs/building-and-deps.md

@@ -0,0 +1,117 @@
+# Building and dependencies
+
+How to build Jolt from source and how to pull Clojure libraries into a project.
+
+## Building
+
+```bash
+git clone https://github.com/jolt-lang/jolt.git
+cd jolt
+git submodule update --init   # vendor/sci (used by the SCI bootstrap tests)
+jpm build
+```
+
+This produces two executables under `build/`:
+
+- **`jolt`** — the runtime: REPL, file/expr runner, nREPL server. The whole `.clj`
+  standard library (`clojure.string`/`set`/`walk`/`edn`/`zip`, `jolt.http`/
+  `interop`/`shell`/`nrepl`) is baked into this binary at build time, so it loads
+  from any directory — the build artifact is self-contained. (`clojure.core` is
+  built into the runtime in Janet and auto-referred, so it's always available.)
+- **`jolt-deps`** — a separate tool that resolves a `deps.edn` (see below). It
+  sits beside the runtime the way `jpm` sits beside `janet`; the runtime itself
+  knows nothing about deps.edn.
+
+Needs `jpm` and a recent Janet — developed and CI-tested against **1.41**. The
+futures and core.async layers use Janet's threaded `ev/` channels (`ev/thread`,
+`ev/thread-chan`), so older Janets may not run the full suite.
+
+`jpm build` doesn't always notice source changes; run `jpm clean && jpm build`
+after editing `src/` to be sure the binaries are current. `jpm test` runs against
+the source directly, so it never goes stale.
+
+## How namespaces are found
+
+`(require ...)` resolves a namespace to a file by searching an ordered list of
+source roots — the stdlib first, then any extra roots — trying `<ns>.clj` then
+`<ns>.cljc` (dots become directories, dashes become underscores). Extra roots
+come from:
+
+- `JOLT_PATH` — a colon-separated list of directories (like a classpath), applied
+  at runtime;
+- the `:paths` option to `init` when embedding Jolt as a library.
+
+If a namespace isn't found on any root, the loader falls back to the stdlib baked
+into the binary — that's how `clojure.string` and friends resolve when you run
+the binary outside the source tree.
+
+So you can point Jolt at a directory of Clojure source with no deps machinery at
+all:
+
+```bash
+JOLT_PATH=/path/to/lib/src build/jolt myfile.clj
+```
+
+## Dependencies via deps.edn
+
+`jolt-deps` reads a `deps.edn` in the current directory, fetches its
+dependencies, and runs `jolt` with the resolved source directories on
+`JOLT_PATH`.
+
+```bash
+jolt-deps path             # print the resolved roots (':'-joined)
+jolt-deps run FILE [args]  # resolve, then run `jolt FILE …`
+jolt-deps repl             # resolve, then start a REPL
+jolt-deps -e EXPR [args]   # resolve, then evaluate EXPR
+```
+
+`jolt-deps` launches the `jolt` binary it finds on `PATH` (override with
+`$JOLT_BIN`).
+
+Example `deps.edn`:
+
+```clojure
+{:paths ["src"]
+ :deps {weavejester/medley {:git/url "https://github.com/weavejester/medley"
+                            :git/tag "1.0.0"}
+        my/helpers          {:local/root "../helpers"}}}
+```
+
+```bash
+jolt-deps run -m myapp.main
+```
+
+### What's supported
+
+- **git deps** — `{:git/url … :git/tag …}` or `{:git/url … :git/sha …}` (use a
+  full SHA; `git fetch` can't resolve a short one). Transitive deps from each
+  dependency's own `deps.edn` are resolved too.
+- **local deps** — `{:local/root "../path"}`.
+- The project's own `:paths` (default `["src"]`) are included.
+
+Resolution reuses jpm's git fetch and cache (a dependency is cloned once into
+`jpm_tree/.cache` and reused). Resolved roots are cached on a hash of `deps.edn`,
+so an unchanged `deps.edn` doesn't re-fetch.
+
+### What's not
+
+- **No Maven.** `:mvn/version` deps are ignored — git and local only.
+- **Pure `clj`/`cljc` only.** A library that needs the JVM (Java interop, host
+  classes) or a `clojure.core` feature Jolt doesn't implement will fail to load
+  or fail at a call. Coverage is per-function: a namespace can load with most
+  functions working and a few not.
+
+### Bundling into one file
+
+`jolt uberscript OUT.clj -m NS` (or `jolt-deps uberscript …`, which resolves deps
+first) bundles `NS` and every namespace it requires — your code plus its
+dependencies — into a single `.clj` in dependency order, ending with a call to
+`NS/-main`. The result runs on a plain `jolt` with no `JOLT_PATH`, no deps
+fetched, and no jpm:
+
+```bash
+jolt-deps uberscript app.clj -m myapp.main
+jolt app.clj arg1 arg2
+```
+
+See [`tools-deps.md`](tools-deps.md) for the design rationale.