refactor!: rewire the plugin onto the kettle binary, and rename it

BREAKING: the plugin is `kettle`, not `tea`, and its commands are `/kettle:*`.
It also now needs a binary on PATH that it did not need before; the README and
every skill say how to get one and what a missing one looks like.

The plugin was 3800 lines of Python doing what a compiled binary does better,
and the name pointed at a tool that no longer takes part: `tea` is Gitea's CLI,
and since the transport moved into the binary nothing here shells out to it for
issues at all. A plugin named after it was going to keep suggesting otherwise.

Deleted: 19 scripts, the 14-file unittest suite, and the tea-guard hook. The
guard blocked any `tea` invocation that would run under a login the model picked
instead of the operator; the binary holds its own credentials and reads the
pinned login out of the project's own config, so that failure is no longer
expressible and there is nothing left to police. agents-sync stays — it is about
AGENTS.md symlinks and has nothing to do with any of this.

What the plugin keeps is what only a plugin can carry: the rules an operator
states and a binary cannot enforce. `init` still refuses to run inside a linked
worktree and still may not be model-invoked, because which directory is the
project is a statement a person makes. The issue format reference stays here and
stays the source of truth. The runner subagent is still for batches and still
may not decide what an issue says.

The command reference in the issue, sync and project skills is GENERATED from
the binary's own command registry, between markers, so a flag that changed
cannot ship with a skill that recommends the old one. `kettle gen skills
--check` exits non-zero when they drift. The generator owns the region and
nothing outside it: the frontmatter description, which is what decides whether a
skill loads at all, stays hand-written.

`use` survives and is the one place `tea` is still named — for releases,
webhooks and actions, which kettle does not cover. Its instruction to write
`--login "$GITEA_LOGIN"` and let the hook substitute the pin was true until this
commit and is now rewritten: `tea` keeps its own configuration, kettle keeps
its own, and configuring one configures nothing in the other.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

plugins/kettle/skills/init/SKILL.md

@@ -0,0 +1,79 @@
+---
+name: init
+description: Make THIS directory a project that tracks issues — run `kettle init`, which creates the `.kettle/` marker every other command resolves the store from, migrates an older store in, and gitignores it. Operator-invoked only; carries the rules the binary cannot enforce — never inside a linked worktree, never an `--at` nobody named, never a migration clash resolved for them.
+argument-hint: "[--at DIR] [--login NAME] [--repo owner/name] [--dry-run]"
+disable-model-invocation: true
+allowed-tools: Bash(kettle init:*), Bash(kettle config:*), Bash(git rev-parse:*)
+---
+
+# /kettle:init — make this directory a project
+
+Initializing is a statement, and the operator makes it: *this* directory is the
+project whose issues live in it. Nothing infers it — `.git` is in every clone,
+and a tool that inferred its root from one wrote other projects' issues into its
+own versioned cache. It is answered once, by a person, and every command
+downstream reads the answer instead of guessing.
+
+The binary does the work and is idempotent. What this skill carries is the three
+things it cannot decide for itself.
+
+## Steps
+
+1. **Refuse inside a linked worktree.** Two different paths mean one:
+
+   ```bash
+   git rev-parse --path-format=absolute --git-dir --git-common-dir
+   ```
+
+   Stop and say so. `.kettle/` is gitignored, so a worktree has no marker by
+   design and reaches the main checkout's store on its own — the walk crosses to
+   it through the `gitdir:` in the `.git` *file*. A marker here gives one project
+   two stores, and the second is deleted with the branch. If anything needs
+   initializing it is the main checkout, which is the second path's parent.
+
+2. Run it, passing the operator's arguments through unchanged:
+
+   ```bash
+   kettle init $ARGUMENTS
+   ```
+
+   With no `--at` it initializes the current directory. **Never supply an `--at`
+   the operator did not name.** Which directory is the project is the one
+   question this command exists to have a person answer; picking a plausible one
+   is the failure the marker replaces.
+
+3. Report what it printed, verbatim. `already initialized — nothing to do` is a
+   success, not something to work around.
+
+`--login` pins a login by name and `--repo` names the tracker repository; both
+are optional and both can be added later by running `init` again — it writes the
+config without disturbing settings it was not given. Neither is a credential:
+the tokens live in one file per machine, `/kettle:auth`.
+
+## When it stops
+
+- **A name clash on the migration** — the same file name on both sides. It exits
+  having changed nothing and names the files. Report that. Do **not** move,
+  delete, or merge either side: one of them may be an `origin: local` issue,
+  which *is* the issue and the only copy of that work. The operator decides
+  which survives.
+- **A marker already exists above this directory.** A second one gives that
+  project a second store and the nearer one wins. Confirm with the operator
+  before going ahead; usually they are standing in a subdirectory and there is
+  nothing to do.
+
+**No `kettle` on PATH?** `command not found: kettle` is the whole story. Stop and
+tell the operator to install it: `cd cli && go build -o ~/.local/bin/kettle
+./cmd/kettle` in the marketplace repository (go.mod requires **go 1.26**), or
+`go install git.noodles.cam/claude-skills/marketplace/cli/cmd/kettle@latest`.
+
+## After
+
+- `/kettle:issue` works now — offline, no login, no network.
+- `/kettle:auth` puts a token on this machine and pins the login this project
+  runs under; needed only for the tracker side, `/kettle:sync`.
+- `kettle config` prints every path and setting this directory resolved to, and
+  is the first thing to run when something looks like it landed in the wrong
+  place.
+
+The full flag table for `init` is the generated block in `/kettle:project`.