feat(cli): pic init scaffolds a new declarative project

Offline project scaffolding — the on-ramp to pull/plan/apply. Writes a
`picloud.toml` describing a minimal *working* app (a `hello` endpoint
bound to GET /hello) plus commented examples for the other blocks,
`scripts/hello.rhai`, and a `.gitignore` that pre-ignores the project
tool's `.picloud/` link-state directory (the home for the bound-plan
state token, landing next). Refuses to overwrite an existing manifest
without `--force`; derives the app slug from the directory name when not
given (validated against the canonical slug rule).

The active manifest is rendered through the same `to_toml` model the rest
of the tool uses, so a freshly-init'd project is guaranteed valid and
immediately `pic plan`-able. Offline — no server contact, so the journey
tests need no DATABASE_URL.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/picloud-cli/tests/cli.rs

@@ -20,6 +20,7 @@ mod apps;
 mod auth;
 mod dead_letters;
 mod email_queue;
+mod init;
 mod invoke;
 mod logs;
 mod output;