docs: use <repo>/<rel path> links throughout, document the convention

All cross-skill links now spell out the repository: skills-public/foo.md,
skills-private/bar.md. These resolve from the shared parent directory, so one
spelling works from either repo and from code-languages/ subdirectories —
replacing the previous mix of ./, ../ and absolute file:// URLs. Link labels
normalised to match. Convention added to the README conventions list.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -8,20 +8,20 @@ A collection of public, reusable agent skills, cheatsheets, and operational work
 
 | Skill File | Scope / Topics Covered |
 | :--- | :--- |
-| **[`coding-dev.md`](./coding-dev.md)** | Standing rules for all code work: maximum linter/compiler strictness, never filtering build output, reuse-before-reinvent dependency ordering, file/function size limits, test & regression discipline, verification gates, scope control, commit hygiene, and honest reporting. |
-| **[`cli-tooling.md`](./cli-tooling.md)** | Using command-line tools correctly: reading the help tree instead of guessing flags, preferring an existing CLI over an ad-hoc script, non-interactive invocation, machine-readable output formats, orienting on prior work before starting, script placement & symlinking, and care around destructive commands. |
+| **[`coding-dev.md`](skills-public/coding-dev.md)** | Standing rules for all code work: maximum linter/compiler strictness, never filtering build output, reuse-before-reinvent dependency ordering, file/function size limits, test & regression discipline, verification gates, scope control, commit hygiene, and honest reporting. |
+| **[`cli-tooling.md`](skills-public/cli-tooling.md)** | Using command-line tools correctly: reading the help tree instead of guessing flags, preferring an existing CLI over an ad-hoc script, non-interactive invocation, machine-readable output formats, orienting on prior work before starting, script placement & symlinking, and care around destructive commands. |
 
-### 🔤 Per-Language Rules ([`code-languages/`](./code-languages/))
+### 🔤 Per-Language Rules ([`code-languages/`](skills-public/code-languages/))
 
 | Language | Skill File | Highlights |
 | :--- | :--- | :--- |
-| **Rust** | [`rust.md`](./code-languages/rust.md) | `--workspace` clippy gate, `[workspace.lints]` single source of truth, no `unwrap`/`unsafe`, core-crate split |
-| **TypeScript / JavaScript** | [`js-typescript.md`](./code-languages/js-typescript.md) | TS > JSDoc > plain JS, banned constructs table, React & hooks rules, resource lifecycle, sandbox boundaries |
-| **Bash / Shell** | [`bash.md`](./code-languages/bash.md) | `set -euo pipefail`, shellcheck, no wait loops, destructive-command guards, build-gate structure |
-| **Python** | [`python.md`](./code-languages/python.md) | `mypy --strict`, broad ruff rule set, asyncio task discipline, rate-limit queueing |
-| **Go** | [`go.md`](./code-languages/go.md) | strict `golangci-lint` set, concrete types over `interface{}`, context everywhere, CGO-free static builds |
-| **C# / .NET** | [`csharp-dotnet.md`](./code-languages/csharp-dotnet.md) | `TreatWarningsAsErrors`, nullable enabled, no `.Result`, trimming/single-file publish caveats, SDK shims |
-| **C / C++** | [`c-cpp.md`](./code-languages/c-cpp.md) | full warning set + `-Werror`, sanitizers, RAII/Rule of Zero, target-based CMake, FFI ownership |
+| **Rust** | [`rust.md`](skills-public/code-languages/rust.md) | `--workspace` clippy gate, `[workspace.lints]` single source of truth, no `unwrap`/`unsafe`, core-crate split |
+| **TypeScript / JavaScript** | [`js-typescript.md`](skills-public/code-languages/js-typescript.md) | TS > JSDoc > plain JS, banned constructs table, React & hooks rules, resource lifecycle, sandbox boundaries |
+| **Bash / Shell** | [`bash.md`](skills-public/code-languages/bash.md) | `set -euo pipefail`, shellcheck, no wait loops, destructive-command guards, build-gate structure |
+| **Python** | [`python.md`](skills-public/code-languages/python.md) | `mypy --strict`, broad ruff rule set, asyncio task discipline, rate-limit queueing |
+| **Go** | [`go.md`](skills-public/code-languages/go.md) | strict `golangci-lint` set, concrete types over `interface{}`, context everywhere, CGO-free static builds |
+| **C# / .NET** | [`csharp-dotnet.md`](skills-public/code-languages/csharp-dotnet.md) | `TreatWarningsAsErrors`, nullable enabled, no `.Result`, trimming/single-file publish caveats, SDK shims |
+| **C / C++** | [`c-cpp.md`](skills-public/code-languages/c-cpp.md) | full warning set + `-Werror`, sanitizers, RAII/Rule of Zero, target-based CMake, FFI ownership |
 
 Each language file extends `coding-dev.md` rather than repeating it. A project's own
 `AGENTS.md` / `CLAUDE.md` / `.rules` always overrides both.
@@ -47,3 +47,10 @@ These skill documents are compatible across agentic developer assistants and env
 - **Codex**: Include in workspace instructions or agent configuration.
 - **Antigravity**: Mount or reference from workspace `.agents/skills/` or global `~/.gemini/config/skills/`.
 - **Other AI Tools (Cursor, OpenCode, Aider, Devin)**: Include as persistent project rules or context files.
+6. **Link between skills as `<repo>/<relative path>`** — e.g.
+   `` [`cli-tooling.md`](skills-public/cli-tooling.md) `` or
+   `` [`network.md`](skills-private/network.md) ``. Links resolve from the shared parent
+   directory holding both repos, so the same spelling works from either repo and from any
+   subdirectory. Never `./`, `../`, or absolute `file://` paths. The sole exception is the
+   per-agent profile files, which state each repository root once in full, since they are
+   loaded as global instructions with no implied working directory.