ADR-0024 Phase F (minimal): drop chumsky from the parse path

Delete the chumsky-side command_parser and its per-command
sub-parsers, error humanisation helpers, and keyword/punct/
ident/value-literal combinators. The unified-grammar walker
in `crate::dsl::walker` is now the sole parse path.

parse_tokens flow (post-Phase F):
1. lex(input) — still produces the Token stream that
   completion / highlighting / echo-line consumers depend on.
2. try_walker_route(source) — walker handles every entry
   keyword in REGISTRY (20 commands across 14 entry words).
3. unknown_command_error(source) — synthetic ParseError for
   inputs whose first identifier-shape token isn't a
   registered entry word. Wording mirrors the chumsky-side
   "expected one of `add`, `change`, …, found `<word>`"
   structural error the legacy top-level Choice produced.

Cargo.toml: chumsky dependency dropped (no remaining uses).
Cargo.lock regenerated; ~58 lines net reduction in the
dependency graph.

Scope intentionally deferred (separate follow-up):
- dsl/lexer.rs, dsl/keyword.rs, dsl/ident_slot.rs,
  dsl/usage.rs::REGISTRY: still consumed by completion.rs,
  input_render.rs, app.rs, theme.rs, db.rs, runtime.rs,
  friendly/keys.rs. Removing these requires migrating each
  consumer to the walker's per-byte-class output / grammar
  REGISTRY / IdentSource enum. Substantial blast radius;
  worth a dedicated session.
- parse.token.keyword.* catalog entries (40+): used by
  usage.rs and parse-error rendering for the unmigrated
  consumers above. Collapse follows after the consumer
  migration.

Tests:
- All existing parser tests (`dsl::parser::tests`) ported in
  place; they call `parse_command` which now flows through
  the walker. 844 passed, 0 failed, 1 ignored — same count
  as Phase E (no test additions, no regressions).
- cargo clippy --all-targets -- -D warnings clean.
- cargo build (release-like dev profile) succeeds.

Cargo.lock

@@ -29,15 +29,6 @@ version = "1.0.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 
-[[package]]
-name = "ar_archive_writer"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7eb93bbb63b9c227414f6eb3a0adfddca591a8ce1e9b60661bb08969b87e340b"
-dependencies = [
- "object",
-]
-
 [[package]]
 name = "arbitrary"
 version = "1.4.2"
@@ -164,20 +155,6 @@ dependencies = [
  "rand_core 0.10.1",
 ]
 
-[[package]]
-name = "chumsky"
-version = "0.13.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e0d2bfadce76f963d776feff99db6dc33783829539258314776383b33e2a00f8"
-dependencies = [
- "hashbrown 0.15.5",
- "regex-automata",
- "serde",
- "stacker",
- "unicode-ident",
- "unicode-segmentation",
-]
-
 [[package]]
 name = "compact_str"
 version = "0.9.0"
@@ -657,8 +634,6 @@ version = "0.15.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
 dependencies = [
- "allocator-api2",
- "equivalent",
  "foldhash 0.1.5",
 ]
 
@@ -1059,15 +1034,6 @@ dependencies = [
  "objc2-core-foundation",
 ]
 
-[[package]]
-name = "object"
-version = "0.37.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff76201f031d8863c38aa7f905eca4f53abbfa15f609db4277d44cd8938f33fe"
-dependencies = [
- "memchr",
-]
-
 [[package]]
 name = "once_cell"
 version = "1.21.4"
@@ -1260,16 +1226,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "psm"
-version = "0.1.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "645dbe486e346d9b5de3ef16ede18c26e6c70ad97418f4874b8b1889d6e761ea"
-dependencies = [
- "ar_archive_writer",
- "cc",
-]
-
 [[package]]
 name = "quote"
 version = "1.0.45"
@@ -1414,7 +1370,6 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "base64",
- "chumsky",
  "crossterm",
  "csv",
  "directories",
@@ -1722,19 +1677,6 @@ dependencies = [
  "wasm-bindgen",
 ]
 
-[[package]]
-name = "stacker"
-version = "0.1.24"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "640c8cdd92b6b12f5bcb1803ca3bbf5ab96e5e6b6b96b9ab77dabe9e880b3190"
-dependencies = [
- "cc",
- "cfg-if",
- "libc",
- "psm",
- "windows-sys",
-]
-
 [[package]]
 name = "static_assertions"
 version = "1.1.0"