chore[bc]: embed addon interface refactor - remove BaseInference and WeightsProvider

[donriddo]

🎯 What problem does this PR solve?

• Embed addon extends BaseInference and uses the WeightsProvider download layer, so the constructor always needs a Loader even when model files are already on disk.
• Native C++ event vocabulary is normalized inline in index.js, spreading bridge logic across the class.

📝 How does it solve it?

• Remove BaseInference inheritance; compose createJobHandler() + exclusiveRunQueue() from @qvac/infer-base@^0.4.0 directly.
• Constructor now takes { files: { model: string[] }, config?, logger?, opts? } with pre-resolved absolute paths. For sharded models the caller passes the full ordered list (<base>.tensors.txt first, then each shard).
• Shard streaming via bare-fs.createReadStream directly (no WeightsProvider).
• Extract native event normalization into addon.js (mapAddonEvent) so the binding wrapper owns the C++ event vocabulary; the JS class only sees logical events (Output, Error, JobEnded).
• Constructor validation: throws TypeError('files.model must be a non-empty array of absolute paths') for missing/empty input.
• run()-before-load() guard: throws Error('Addon not initialized. Call load() first.') instead of dereferencing null.
• load() on an already-loaded instance is now a silent no-op (ReadyResource pattern). Call unload() first if you intend to swap weights, then load() again.
• load() is serialized through the same exclusiveRunQueue as run() and unload(), so two concurrent load() calls on the same instance no longer race past the configLoaded guard and leak a native handle.
• Constructor now validates each files.model entry with path.isAbsolute(). Relative paths are rejected at construction time instead of bubbling up from bare-fs or the native load.
• Crash-safe shard streaming: partial load failure best-effort-unloads and nulls this.addon.
• unload() clears this.addon and state.configLoaded so post-unload calls hit the guards instead of dereferencing a disposed native handle.
• Unknown addon events are now logged at warn level (these indicate a native-layer change worth surfacing), not forwarded to the response output stream.
• Dependency changes: @qvac/infer-base ^0.2.2 → ^0.4.0, bare-fs moved to runtime dependencies, @qvac/dl-filesystem and @qvac/dl-hyperdrive removed.
• README and docs updated; addon.js JSDoc trimmed of internal task-doc references.

🧪 How was it tested?

• npm run lint (standard) and npm run test:dts clean.
• New unit test test/unit/map-addon-event.test.js — 9 tests covering stats detection, backendDevice mapping (0 → cpu, 1 → gpu), Error/Embeddings event names, stats precedence over event name, and null-returns for unknown shapes.
• Integration tests and examples migrated to the new constructor shape; all pass locally.

💥 Breaking Changes

BEFORE (≤ 0.13.x):

const FilesystemDL = require('@qvac/dl-filesystem')
const loader = new FilesystemDL({ dirPath: '/models' })
const model = new GGMLBert({
  loader,
  modelName: 'bge-small-en-v1.5-q4_0.gguf',
  diskPath: '/models',
  logger: console,
  opts: { stats: true }
}, { device: 'gpu', batch_size: '512' })

AFTER (0.14.0):

const model = new GGMLBert({
  files: { model: ['/models/bge-small-en-v1.5-q4_0.gguf'] },
  config: { device: 'gpu', batch_size: '512' },
  logger: console,
  opts: { stats: true }
})

Additional behavior changes:

• In-memory streaming from network sources is no longer supported — the SDK does not use it today (stores models to disk first); can be re-added via a future loader abstraction. Previously possible through the Loader abstraction.
• Second load() is a silent no-op (ReadyResource pattern). Call unload() first if you intend to swap weights.
• downloadWeights, the Loader interface, and loader-based progress callbacks are gone.

🔌 API Changes

// Constructor: single object with files.model (string array of absolute paths)
// Removed: downloadWeights(), Loader interface, WeightsProvider, BaseInference inheritance
// Removed deps: @qvac/dl-filesystem (devDep), @qvac/dl-hyperdrive (peerDep)
// Kept: load(), run(), cancel(), unload()
// Added: getState()

[maxim-smotrov]

Please fix the mermaid diagrams syntax.

[donriddo]

/review

[gianni-cor]

/review

[gianni-cor]

/review