feat: Phase 8.2, 8.4, 8.5, 9.1 + C backend fixes

Phase 8.2 — Gradual Ownership:
- Add tkRef/tkMutRef types and `mut` keyword
- Add @[Checked] attribute for opt-in borrow checking
- Reject assignment through &T in checked functions
- examples/ownership.bux

Phase 8.4 — CTFE:
- Evaluate const func at compile-time via evalExpr/evalBlock
- Fold const declarations to literals; emit #define in C
- examples/ctfe.bux (Factorial(10) → 3628800)

Phase 8.5 — Trait Bounds:
- Change declFuncTypeParams from seq[string] to seq[TypeParam] (name + bound)
- Parser handles <T: Comparable>
- Sema checks typeImplements at call sites
- Fix C backend: generic receivers + pointer self field access
- examples/trait_bounds.bux

Phase 9.1 — Package Manager:
- Inline tables/arrays in TOML parser
- bux add, bux install, bux.lock generation
- Dependency resolution with git/path sources
- Build pipeline merges dependency .bux sources

C Backend Fixes:
- resolveExprType(ekIdent) now applies typeSubst for generic params
- Method desugaring works for monomorphized generic receivers
- Pointer checks use isPointer (covers tkRef/tkMutRef)
- Field access on &T emits -> instead of .

Remove accidentally committed test binaries from tracking

docs/Packages.md

@@ -0,0 +1,130 @@
+# Bux Package Manager
+
+> **Status:** Implemented (Phase 9.1) | **Format:** Compatible with Rux.toml spec
+
+---
+
+## Manifest (`bux.toml`)
+
+Every Bux package has a `bux.toml` at the project root.
+
+```toml
+[Package]
+Name    = "MyApp"
+Version = "0.1.0"
+Type    = "bin"          # bin | lib | shared | static
+Authors = ["Your Name <you@example.com>"]
+License = "MIT"
+
+[Build]
+Output = "Bin"
+
+[Dependencies]
+Std  = "1.0"
+Json = { Version = "2.1", Source = "https://github.com/bux-lang/json" }
+Utils = { Path = "../Utils" }
+```
+
+### Dependency Forms
+
+| Form | Example | Description |
+|------|---------|-------------|
+| Version string | `Std = "1.0"` | Registry dependency |
+| Wildcard | `Std = "*"` | Latest version |
+| Inline table (git) | `{ Version = "1.4", Source = "https://..." }` | Git URL + version |
+| Inline table (path) | `{ Path = "../Lib" }` | Local path dependency |
+
+---
+
+## CLI Commands
+
+### `bux add <name> [version]`
+
+Add a dependency to `bux.toml`.
+
+```bash
+# Add registry dependency
+bux add json "2.1"
+
+# Add path-based dependency
+bux add utils --path "../utils"
+
+# Add git dependency
+bux add network --git "https://github.com/bux-lang/network"
+```
+
+### `bux install`
+
+Resolve dependencies and generate `bux.lock`.
+
+```bash
+bux install
+```
+
+What it does:
+1. Reads `[Dependencies]` from `bux.toml`
+2. Resolves path-based deps (verifies directory exists)
+3. Clones/pulls git-based deps to `~/.bux/packages/<name>/`
+4. Generates `bux.lock` with exact versions and sources
+
+### `bux build` / `bux run`
+
+Automatically reads `bux.lock` and merges dependency source files into the build.
+
+```bash
+bux build   # Compile with all dependencies
+bux run     # Build and run
+```
+
+---
+
+## Lockfile (`bux.lock`)
+
+Auto-generated. **Do not edit manually.**
+
+```toml
+[[Package]]
+Name = "json"
+Version = "2.1.3"
+Source = "https://github.com/bux-lang/json"
+Checksum = "8dcb2a7f..."
+
+[[Package]]
+Name = "utils"
+Version = "0.1.0"
+Source = "/home/user/projects/utils"
+```
+
+The lockfile ensures **reproducible builds** — every developer gets the exact same dependency versions.
+
+---
+
+## Dependency Resolution Rules
+
+1. **Path-based** deps are resolved relative to the manifest directory
+2. **Git-based** deps are cloned to `~/.bux/packages/<name>/`
+3. **Version-based** deps (without Source) require a registry (future feature)
+4. Dependencies are loaded from `<dep>/src/*.bux` at build time
+5. Later declarations shadow earlier ones (project > deps > stdlib)
+
+---
+
+## Example: Creating a Library
+
+```bash
+bux new mylib
+cd mylib
+# Edit src/Main.bux → module MyLib { pub func Add(...) }
+bux build       # Builds as library (Type = "lib")
+```
+
+## Example: Using a Library
+
+```bash
+bux new myapp
+cd myapp
+bux add mylib --path "../mylib"
+bux install
+# Edit src/Main.bux → import MyLib::Add;
+bux run
+```