feat: #146 — wire claw config and claw diff as standalone subcommands

## Problem

`claw config` and `claw diff` are pure-local read-only introspection
commands (config merges .claw.json + .claw/settings.json from disk; diff
shells out to `git diff --cached` + `git diff`). Neither needs a session
context, yet both rejected direct CLI invocation:

$ claw config
error: `claw config` is a slash command. Use `claw --resume SESSION.jsonl /config` ...

$ claw diff
error: `claw diff` is a slash command. ...

This forced clawing operators to spin up a full session just to inspect
static disk state, and broke natural pipelines like
`claw config --output-format json | jq`.

## Root cause

Sibling of #145: `SlashCommand::Config { section }` and
`SlashCommand::Diff` had working renderers (`render_config_report`,
`render_config_json`, `render_diff_report`, `render_diff_json_for`)
exposed for resume sessions, but the top-level CLI parser in
`parse_subcommand()` had no arms for them. Zero-arg `config`/`diff`
hit `parse_single_word_command_alias`'s fallback to
`bare_slash_command_guidance`, producing the misleading guidance.

## Changes

### rust/crates/rusty-claude-cli/src/main.rs

- Added `CliAction::Config { section, output_format }` and
  `CliAction::Diff { output_format }` variants.
- Added `"config"` / `"diff"` arms to the top-level parser in
  `parse_subcommand()`. `config` accepts an optional section name
  (env|hooks|model|plugins) matching SlashCommand::Config semantics.
  `diff` takes no positional args. Both reject extra trailing args
  with a clear error.
- Added `"config" | "diff" => None` to
  `parse_single_word_command_alias` so bare invocations fall through
  to the new parser arms instead of the slash-guidance error.
- Added dispatch in run() that calls existing renderers: text mode uses
  `render_config_report` / `render_diff_report`; JSON mode uses
  `render_config_json` / `render_diff_json_for` with
  `serde_json::to_string_pretty`.
- Added 5 regression assertions in parse_args test covering:
  parse_args(["config"]), parse_args(["config", "env"]),
  parse_args(["config", "--output-format", "json"]),
  parse_args(["diff"]), parse_args(["diff", "--output-format", "json"]).

### ROADMAP.md

Added Pinpoint #146 documenting the gap, verification, root cause,
fix shape, and acceptance. Explicitly notes which other slash commands
(`hooks`, `usage`, `context`, etc.) are NOT candidates because they
are session-state-modifying.

## Live verification

$ claw config   # no config files
Config
  Working directory /private/tmp/cd-146-verify
  Loaded files      0
  Merged keys       0
Discovered files
  user    missing ...
  project missing ...
  local   missing ...
Exit 0.

$ claw config --output-format json
{
  "cwd": "...",
  "files": [...],
  ...
}

$ claw diff   # no git
Diff
  Result           no git repository
  Detail           ...
Exit 0.

$ claw diff --output-format json   # inside claw-code
{
  "kind": "diff",
  "result": "changes",
  "staged": "",
  "unstaged": "diff --git ..."
}
Exit 0.

## Tests

- rusty-claude-cli bin: 177 tests pass (5 new assertions in parse_args)
- Full workspace green except pre-existing resume_latest flake (unrelated)

## Not changed

`hooks`, `usage`, `context`, `tasks`, `theme`, `voice`, `rename`,
`copy`, `color`, `effort`, `branch`, `rewind`, `ide`, `tag`,
`output-style`, `add-dir` — all session-mutating or interactive-only;
correctly remain slash-only.

Closes ROADMAP #146.

ROADMAP.md

@@ -5578,3 +5578,44 @@ MCP
 **Blocker.** None. `CliAction::Plugins` already exists with a working dispatcher.
 
 **Source.** Jobdori dogfood 2026-04-21 19:30 KST on main HEAD `faeaa1d` in response to Clawhip nudge. Joins **prompt misdelivery** cluster. Session tally: ROADMAP #145.
+
+## Pinpoint #146. `claw config` and `claw diff` are pure-local introspection commands but require `--resume SESSION.jsonl` wrapping
+
+**Gap.** Running `claw config` or `claw diff` directly exits with an error pointing to `claw --resume SESSION.jsonl /config` as the only path. Both commands are pure, read-only introspection: `config` reads files from disk and merges them; `diff` shells out to `git diff --cached` + `git diff`. Neither needs a session context to produce correct output.
+
+**Verified on main HEAD `7d63699` (2026-04-21 20:03 KST):**
+
+```
+$ claw config
+error: `claw config` is a slash command. Use `claw --resume SESSION.jsonl /config` or start `claw` and run `/config`.
+
+$ claw config --output-format json
+{"error":"`claw config` is a slash command. ...","type":"error"}
+
+$ claw diff
+error: `claw diff` is a slash command. Use `claw --resume SESSION.jsonl /diff` or start `claw` and run `/diff`.
+```
+
+Meanwhile `agents`, `mcp`, `skills`, `status`, `doctor`, `sandbox`, `plugins` (after #145) all work standalone.
+
+**Why this is a clawability gap.**
+1. **Synthetic friction**: requires a session file to inspect static disk state. A claw probing configuration has to spin up a session it doesn't need.
+2. **Surface asymmetry**: all other read-only diagnostics are standalone. `config` and `diff` are the remaining holdouts.
+3. **Pipeline-unfriendly**: `claw config --output-format json | jq` and `claw diff | less` are natural operator workflows; both are currently broken.
+4. **Both already have working JSON renderers** (`render_config_json`, `render_diff_json_for`) — infrastructure for top-level wiring exists.
+
+**Fix shape (~30 lines).** Add `"config"` and `"diff"` arms to the top-level parser in `main.rs` (mirroring #145's `plugins` wiring). Each dispatches to a new `CliAction` variant or to existing resume-supported renderers directly. Text mode uses `render_config_report` / `render_diff_report`; JSON mode uses `render_config_json` / `render_diff_json_for`. Remove `config` from `bare_slash_command_guidance`'s fallback allowlist only if explicitly gating (parser arm already short-circuits).
+
+**Acceptance.**
+- `claw config` exits 0 with discovered-file listing + merged-keys count.
+- `claw config --output-format json` emits typed envelope with discovered files and merged JSON.
+- `claw config env` / `claw config plugins` surface specific sections (matches `SlashCommand::Config { section }` semantics).
+- `claw diff` exits 0 with clean-tree message or staged/unstaged summary.
+- `claw diff --output-format json` emits typed envelope.
+- Regression tests: `parse_args(["config"])` → `CliAction::Config`; `parse_args(["diff"])` → `CliAction::Diff`.
+
+**Blocker.** None. Renderers exist and are resume-supported (proving they're pure-local).
+
+**Not applying to.** `hooks` (session-state-modifying, explicitly flagged "unsupported resumed slash command" in main.rs), `usage`, `context`, `tasks`, `theme`, `voice`, `rename`, `copy`, `color`, `effort`, `branch`, `rewind`, `ide`, `tag`, `output-style`, `add-dir` — all session-mutating or interactive-only.
+
+**Source.** Jobdori dogfood 2026-04-21 20:03 KST on main HEAD `7d63699` in response to Clawhip nudge. Joins **surface asymmetry** cluster (#145 sibling). Session tally: ROADMAP #146.