auto-linker + TODO overhaul

new crate: penumbra-auto-link. 158 lines. this is the thing that makes the canvas feel fun.

the pipeline is simple: embed the note, search the vector index for neighbours, create implicit links for anything above the similarity threshold. process_note() takes a Note, embeds its text via the EmbeddingProvider, inserts the embedding into the index (so it’s immediately discoverable by future saves), searches for the top-k closest neighbours, filters by score, checks for duplicates, and creates implicit links in the graph. explicit links are never touched. I don’t mess with your links. (why does that sound funny lol)

configurable: top_k (default 10), min_score (default 0.75), max_links per pass (default 5). the AutoLinker holds Arc references to the embedder, index, graph, and event bus. every new link fires a LinkAdded event so the UI can animate the card drifting to its new neighbours.

the duplicate check matters. between the search returning results and the link being created, another thread could have already linked the same pair. so it locks the graph, checks if the link exists, and only creates it if it doesn’t. two process_note() calls on the same note produce links on the first call and an empty vec on the second.

Some tests in auto_link_matrix.rs: creates implicit links, skips self-links, obeys score threshold, respects max_links cap, handles empty index (no candidates), no duplicate links on re-process, empty body doesn’t panic, top_k=0 returns empty.

also cleaned up some stray em-dashes and arrow symbols in comments across the codebase. vscode keeps auto-correcting -- to em-dashes and -> to the arrow symbol and I keep not noticing until I read the diff. idk if it’s a bug or a feature but it’s annoying.

the TODO got a real overhaul. the old flat checklist is gone. everything that’s done is removed. what’s left is organized into sections: Dioxus UI plans (spring animations, camera lerp, pinned stars, cached positions), WASM worker threading, storage and sync (Google Drive, GitHub repo, offline mode, merge strategy), and future stuff (encrypted vault). it reads like a roadmap now instead of a grocery list.

eleven crates. too much? no.
modularity is never “too much,” rather it’s better to be more modular than less. (unless you have something insane like a file per function)