feat(tests): add shadow-classification lint; fix real cp/mv/less bugs

New Phase 1b in tests/run-tests.fish: catches a bare C1-shadowed-command
call in a functions/*.fish body with no matching uses-shadow(name) or
self-limiting(name) in that function's own CLASSIFICATION header. This
is exactly the check discussed after the rm and cd audits -- runtime
auto-unwrapping isn't viable in fish (there's no hook finer than
shadowing itself, and rewriting behavior invisibly at runtime is its
own footgun); a static lint using the CLASSIFICATION tag as the
declared-intentional marker is. Scoped to functions/*.fish only: the
one-function-per-file convention there makes body extraction exact
with no block-depth parser needed.

Added a new self-limiting(name) tag to the schema for the case a bare
call is safe not because the caller did anything, but because the
shadow's own logic already neutralizes the override: rm's and mkdir's
flag checks (verified precisely -- rm falls back to command rm for any
flag except a bare -r/-R/--recursive alone, which still routes to
trash; mkdir falls back to command mkdir -p for any flag, no
exception), and grep/fgrep/egrep/dir/vdir/cat's own tty auto-detection
(--color=auto, and bat's default color behavior -- verified
byte-identical to stock cat when piped, since bat also auto-disables
highlighting on a non-terminal). Explicit and durable rather than a
silent lint exemption: if a shadow's bypass condition is ever
weakened, every self-limiting site is one grep away instead of
silently wrong.

Running the first draft of the lint surfaced three more real bugs,
none previously audited:

- config-help.fish's --man pager path checks `type -q less` (proving
  it wants the real less binary specifically, for less-only -R/+N
  flag syntax) then called it bare, routing through our own
  $PAGER -> ov -> less -> more -> cat fallback chain instead -- which
  could hand those less-specific flags to a completely different
  program. Now command less.
- _fish_deps_install.fish and _fish_deps_update.fish's binary-upgrade
  paths cp a freshly downloaded binary over an already-installed one
  with no existence guard -- the update flow's target is guaranteed to
  already exist. Our cp shadow forces -i unconditionally (a plain
  alias, not flag-aware like rm's), so this would hang waiting on a
  confirmation prompt in any non-interactive run. Now command cp.
  Same two files' lazydocker install path piped curl output into bare
  bash, invoking our shell-switch wrapper instead of a plain
  subshell. Now command bash.
- agents-init.fish's AGENTS.md/CLAUDE.md relocation calls mv bare in
  four places; each is already guarded by a preceding test -f check on
  the destination, so the -i alias was unlikely to ever fire in
  practice, but explicit command mv removes the reliance on that guard
  entirely rather than leaving it as the only thing standing between a
  file move and an unattended hang.

The remaining ~65 flagged call sites across ~24 files were reviewed
individually and tagged self-limiting(rm)/self-limiting(mkdir)
(verified flagged with -f/-rf or -p) and self-limiting(grep)/
self-limiting(cat) (verified piped, captured, or -q/-c; none display
color to a human), plus uses-shadow(ls) for two existence-check-only
calls (cffetch.fish, ffetch.fish) whose output is redirected to
/dev/null.

docs/function-classification-schema.md

@@ -35,6 +35,26 @@ it empty as a placeholder.
   break this function's logic: timestamps leaking into a parsed capture,
   `-i` prompting on a path meant to run unattended, structural output
   changes breaking a `string`/`sed` parse, etc.
+- **`self-limiting(name[,name...])`** — calls a shadowed command bare, and
+  it's safe not because the caller did anything but because *the shadow's
+  own logic* already neutralizes the override for this call. Verify the
+  actual condition per shadow, it's not the same check for each one:
+  - `rm` falls back to `command rm` for any flag **except** a bare `-r`,
+    `-R`, or `--recursive` (those still route to `trash put`) — so
+    `rm -f`/`rm -rf` qualify, but `rm -r $dir` alone does not.
+  - `mkdir` falls back to `command mkdir -p` for *any* flag at all, no
+    exception.
+  - `--color=auto`/`bat`'s own tty auto-detection (`grep`, `fgrep`,
+    `egrep`, `dir`, `vdir`, `cat` — verified byte-identical to stock when
+    piped or captured, since none of these force color on a
+    non-terminal).
+
+  Document it explicitly rather than leaving the bare call untagged: if a
+  shadow's bypass condition is ever weakened, narrowed, or removed, every
+  `self-limiting` site is one grep away instead of silently wrong.
+  Don't use this for `ls` — eza's long-format/icon layout is structural,
+  not tty-gated, so it stays different from stock `ls` even piped; a
+  bare `ls` call still needs `uses-shadow(ls)` or a real bypass.
 - **`destructive`** — can irreversibly delete or overwrite data: `rm -f`,
   `rm -rf`, truncating or force-overwriting a file, `git push --force`.
   Routine cleanup of the function's own `$tmpdir`/`$_tmpdir`/`mktemp`