docs(bf-10qd4): mark unpublished install channels as coming-soon

- Update badges (crates.io, PyPI) to show 'coming-soon' status
- Add prominent warning that public releases are not yet available
- Reorganize Installation section with development instructions first
- Mark each planned install channel with clear status indicators
- Update distribution table to show which SDKs are not yet published

This addresses the issue where README instructed users to install from
nonexistent artifacts (crates.io, PyPI, Docker Hub, Homebrew).

All install commands now clearly indicate they are planned but not yet
available. Users are directed to build from source instead.

References: bf-10qd4

README.md

@@ -1,7 +1,7 @@
 # pdftract
 
-[![crates.io](https://img.shields.io/crates/v/pdftract)](https://crates.io/crates/pdftract)
-[![PyPI](https://img.shields.io/pypi/v/pdftract)](https://pypi.org/project/pdftract/)
+[![crates.io](https://img.shields.io/badge/crates.io-coming--soon-orange)](https://github.com/jedarden/pdftract/blob/main/docs/plan/plan.md)
+[![PyPI](https://img.shields.io/badge/PyPI-coming--soon-orange)](https://github.com/jedarden/pdftract/blob/main/docs/plan/plan.md)
 [![docs.rs](https://img.shields.io/docsrs/pdftract-core)](https://docs.rs/pdftract-core)
 [![License](https://img.shields.io/badge/license-MIT%20OR%20Apache--2.0-blue)](LICENSE-MIT)
 [![MSRV](https://img.shields.io/badge/MSRV-1.78-orange)](https://blog.rust-lang.org/2024/05/02/Rust-1.78.0.html)
@@ -38,38 +38,64 @@ See [docs/operations/manual-platform-smoke.md](docs/operations/manual-platform-s
 
 ## Installation
 
+**🚧 Public releases coming soon** — pdftract is preparing for its first public release (v0.1.0). The install commands below are planned but not yet available. For now, use the development installation instructions below.
+
 **Minimum Supported Rust Version (MSRV):** 1.78
 
-### Cargo
+### Development installation
+
+Build from source:
 
 ```bash
-cargo add pdftract-core
+# Clone the repository
+git clone https://github.com/jedarden/pdftract.git
+cd pdftract
+
+# Build the CLI
+cargo build --release
+
+# Install the CLI locally
+cargo install --path .
 ```
 
-Or install the CLI:
+### Planned release channels (coming soon)
+
+#### Cargo
 
 ```bash
+# Add as a library dependency
+cargo add pdftract-core
+
+# Or install the CLI
 cargo install pdftract
 ```
 
-### pip
+*Status: Not yet published to crates.io — tracked in [bf-10qd4](https://github.com/jedarden/pdftract/commit/bf-10qd4)*
+
+#### pip
 
 ```bash
 pip install pdftract
 ```
 
-### Docker
+*Status: Not yet published to PyPI — tracked in [bf-10qd4](https://github.com/jedarden/pdftract/commit/bf-10qd4)*
+
+#### Docker
 
 ```bash
 docker pull ronaldraygun/pdftract:latest
 ```
 
-### Homebrew
+*Status: Not yet published to Docker Hub — tracked in [bf-10qd4](https://github.com/jedarden/pdftract/commit/bf-10qd4)*
+
+#### Homebrew
 
 ```bash
 brew install pdftract
 ```
 
+*Status: Not yet submitted to Homebrew — tracked in [bf-10qd4](https://github.com/jedarden/pdftract/commit/bf-10qd4)*
+
 ## Quickstart
 
 ### Rust
@@ -204,12 +230,12 @@ pdftract ships multiple integration surfaces from a single Rust core:
 
 | SDK | Package | Notes |
 |---|---|---|
-| Rust library | [`pdftract-core`](https://crates.io/crates/pdftract-core) on crates.io | Primary API |
-| CLI binary | [`pdftract`](https://crates.io/crates/pdftract) on crates.io | Wraps the library |
-| Python bindings | [`pdftract`](https://pypi.org/project/pdftract/) on PyPI | PyO3-based, wheels for Linux/macOS/Windows |
-| C shared library | `libpdftract` | Stable C ABI; use `pdftract codegen` to generate FFI headers for your language |
-| Docker image | [`ronaldraygun/pdftract`](https://hub.docker.com/r/ronaldraygun/pdftract) | Includes `serve` mode HTTP microservice |
-| HTTP microservice | `pdftract serve` | REST API for language-agnostic integration |
+| Rust library | [`pdftract-core`](https://crates.io/crates/pdftract-core) on crates.io | Primary API — **🚧 coming soon** |
+| CLI binary | [`pdftract`](https://crates.io/crates/pdftract) on crates.io | Wraps the library — **🚧 coming soon** |
+| Python bindings | [`pdftract`](https://pypi.org/project/pdftract/) on PyPI | PyO3-based, wheels for Linux/macOS/Windows — **🚧 coming soon** |
+| C shared library | `libpdftract` | Stable C ABI; use `pdftract codegen` to generate FFI headers for your language — **🚧 coming soon** |
+| Docker image | [`ronaldraygun/pdftract`](https://hub.docker.com/r/ronaldraygun/pdftract) | Includes `serve` mode HTTP microservice — **🚧 coming soon** |
+| HTTP microservice | `pdftract serve` | REST API for language-agnostic integration (build from source) |
 
 Additional language SDK packages (Go, Node.js, Ruby) are in progress, built on top of the C ABI.