fix(shared-context): edition 2024 for let-chains + Option/Result coercion in registry_guard (unblocks fleet bots local build) (#244)

## Summary

The 2026-05-25 migration commit introduced **let-chains** syntax (Rust
2024 only) into
`shared-context/src/{exclusion_registry,registry_guard,storage}.rs`
while `shared-context/Cargo.toml` still declared `edition = "2021"`.
Local builds of every fleet bot (echidnabot, panicbot, seambot,
cipherbot, rhodibot, finishingbot, ...) failed with:

```
error: let chains are only allowed in Rust 2024 or later
```

There was also an `Option`/`Result` type mismatch in
`shared-context/src/registry_guard.rs:127` (and a duplicate copy in
`robot-repo-automaton/src/registry_guard.rs:131`):

```rust
.and_then(|r| r.url().map(|s| s.to_string()));  // r.url() -> Result<&str, Error>, not Option<&str>
```

## Changes

- **`shared-context/Cargo.toml`**: `edition = "2021"` -> `edition =
"2024"` (Option 1, preferred). rustc 1.85+ supports it; CI workflows use
`dtolnay/rust-toolchain@stable`.
- **`shared-context/src/registry_guard.rs:126`**: insert `.ok()` between
`r.url()` and `.map(|s| s.to_string())` to coerce `Result` -> `Option`.
- **`robot-repo-automaton/src/registry_guard.rs:131`**: identical
`.ok()` fix (same duplicated buggy line).

## Verification (cargo check, all green)

- `shared-context` (lib + tests + benches)
- `robot-repo-automaton`
- `dashboard`
- `shared-context/fleet-cli`
- `bots/{accessibilitybot, cipherbot, echidnabot, finishingbot, glambot,
gsbot, panicbot, rhodibot, seambot, the-hotchocolabot}`

## Out of scope (pre-existing, not introduced/fixed here)

- `bots/sustainabot` has a path dep on `bots/panic-attacker/` which does
not exist in-tree (likely a Cargo.toml rename casualty). This break
pre-dates the let-chains regression -- verified by stashing the fix and
re-running `cargo check`.

## Test plan

- [x] `cargo check --all-targets -p gitbot-shared-context` -> green
- [x] `cargo check` in 10 bot crates -> all green
- [x] `cargo check` in `robot-repo-automaton`, `dashboard`, `fleet-cli`
-> all green
- [ ] CI: rust-ci / db-checks / e2e / dogfood / boj-build / cargo-audit
(expected to flip green per blocker chain)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

robot-repo-automaton/src/registry_guard.rs

@@ -128,7 +128,7 @@ fn repo_identity(repo_path: &Path) -> (Option<String>, Option<String>) {
     let origin_url = repo
         .find_remote("origin")
         .ok()
-        .and_then(|r| r.url().map(|s| s.to_string()));
+        .and_then(|r| r.url().ok().map(|s| s.to_string()));
     let full_name = origin_url.as_deref().and_then(parse_full_name);
     (full_name, origin_url)
 }

shared-context/Cargo.toml

@@ -2,7 +2,7 @@
 [package]
 name = "gitbot-shared-context"
 version = "0.1.0"
-edition = "2021"
+edition = "2024"
 authors = ["Hyperpolymath <dev@hyperpolymath.org>"]
 description = "Shared context layer for gitbot-fleet coordination"
 license = "MPL-2.0"

shared-context/src/registry_guard.rs

@@ -123,7 +123,7 @@ fn repo_identity(repo_path: &Path) -> (Option<String>, Option<String>) {
     let origin_url = repo
         .find_remote("origin")
         .ok()
-        .and_then(|r| r.url().map(|s| s.to_string()));
+        .and_then(|r| r.url().ok().map(|s| s.to_string()));
     let full_name = origin_url.as_deref().and_then(parse_full_name);
     (full_name, origin_url)
 }