fix: compatibility with Obsidian 1.7+; migrate build to esbuild

[edejong-source]

Closes #78. The plugin currently doesn't load on Obsidian 1.7+ — two compatibility issues, plus a build that no longer runs on current Node.

Source fixes

1. Null-safe sidebar leaf opening. obsidian-community-lib's openView calls app.workspace.getRightLeaf(false) / getLeftLeaf(false) and immediately awaits setViewState on the result. Obsidian 1.7+ returns null from those when the sidebar panel doesn't exist, producing an unhandled TypeError on load.

This PR ships a local openView shadow in src/main.ts that falls back to app.workspace.getLeaf(true) (a new center tab) when the side leaf is unavailable. Removes the dependency on the upstream helper for view opening only — wait is still imported from obsidian-community-lib.

2. resolvedLinks indexing-wait infinite loop. resolvedLinksComplete compared Object.keys(resolvedLinks).length === noFiles against the total markdown count. Obsidian's metadataCache.resolvedLinks omits notes that have no outgoing links, so equality never satisfies on any vault containing link-less notes — the onload await wait(1000) loop spins forever. Changed === to >=.

Diagnosis for both originally posted in the issue thread by @northbridgetechnology.

Build migration

The Rollup 2.58 + @rollup/plugin-typescript 8.3 toolchain no longer transforms the entry TypeScript on current Node — the plugin's load hook silently returns null, and Rollup falls back to its native JS parser which dies on the first import type statement.

Rather than chase that, this PR migrates to esbuild + esbuild-svelte, which is what the current obsidian-sample-plugin template uses. The new esbuild.config.mjs mirrors the previous behaviour (inline source maps for dev, none for prod; obsidian + node builtins external; Svelte CSS inlined into the JS bundle). package.json scripts now invoke it. Build is ~10× faster.

The old rollup.config.js and rollup deps are left in tree — happy to remove them in a follow-up if you'd prefer that as a separate change.

Testing

• npm run build produces a 769KB main.js with the patches inlined
• Installed the bundle in an Obsidian 1.9 vault: plugin loads, view opens in the right sidebar (or center tab when sidebar collapsed), graph initialises on vaults with link-less notes
• No regression in the existing a11y warnings from Svelte components (21 pre-existing)