Add streaming flow diagrams, update existing flows with streaming references

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/claude-agent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

docs/architecture/flows/monitor-album-stream-protocol.puml

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+@startuml MonitorAlbumStream Protocol
+skinparam sequenceMessageAlign center
+title MonitorAlbumStream: Message Protocol
+
+participant "Client" as C
+participant "Server" as S
+
+== Stream Initialization ==
+
+C -> S: gRPC MonitorAlbumStream()
+note right: Opens bidirectional stream
+
+== Request Messages (Client -> Server) ==
+
+C -> S: MonitorAlbumStreamRequest
+note right #lightblue
+**oneof message:**
+- **start**: StartMonitorRequest
+  - album_id (required)
+  - quality: LOSSLESS | LOSSY | UNSPECIFIED
+  - mode: AUTOMATIC (0) | MANUAL (1)
+  - indexer_options: {tracker}
+- **decision**: UserDecision
+  - prompt_id (must match pending prompt)
+  - confirm | selected_id | selected_ids
+- **cancel**: CancelRequest
+  - Gracefully terminates workflow
+end note
+
+== Response Messages (Server -> Client) ==
+
+S -> C: MonitorAlbumStreamResponse
+note left #lightgreen
+**oneof message:**
+- **status**: StatusUpdate
+  - step: MonitorStep enum
+  - message: human-readable text
+  - data: StreamAlbumInfo | TorrentList | ReleaseInfo
+- **prompt**: PromptForDecision
+  - prompt_id: unique identifier
+  - type: CONFIRM | SELECT_ONE | SELECT_MANY
+  - message: prompt text
+  - timeout_seconds: response deadline
+  - options: confirm | select_one | select_many config
+- **result**: MonitorAlbumResponse
+  - Final response (stream ends after this)
+- **error**: ErrorUpdate
+  - failed_step: where error occurred
+  - message: error description
+  - recoverable: bool
+end note
+
+== Monitor Steps (Status Updates) ==
+
+note over C, S #lightyellow
+**MonitorStep Enum:**
+1. FETCHING_METADATA - Getting album info from metadata service
+2. CHECKING_OWNED - Checking if already downloaded
+3. SEARCHING_INDEXER - Querying Jackett/indexers
+4. PARSING_RESULTS - Resolving magnets, parsing torrents
+5. FILTERING_QUALITY - Applying quality filter
+6. SELECTING_RELEASE - Choosing best/user-selected release
+7. ADDING_TORRENT - Adding to qBittorrent
+8. SAVING - Persisting to database
+9. COMPLETE - Workflow finished
+end note
+
+== Prompt Types (Manual Mode) ==
+
+note over C, S #orange
+**CONFIRM** (yes/no decision)
+- confirm_label, cancel_label
+- default_value: bool
+
+**SELECT_ONE** (pick one option)
+- options: [{id, label, description}]
+- default_id: pre-selected option
+
+**SELECT_MANY** (pick multiple options)
+- options: [{id, label, description}]
+- default_ids: pre-selected options
+- min_selections, max_selections
+end note
+
+== Data Payloads ==
+
+note over C, S #lightblue
+**StreamAlbumInfo** (at FETCHING_METADATA)
+- artist, title, release_date, already_owned, owned_quality
+
+**TorrentList** (at PARSING_RESULTS)
+- torrents: [{id, title, tracker, seeders, format, lossless}]
+
+**ReleaseInfo** (at SELECTING_RELEASE)
+- info_hash, format, bit_depth, sample_rate, seeders, tracker
+end note
+
+== Timeout Behavior ==
+
+note over C, S #pink
+When prompt times out (max: 300s):
+- Server uses **default decision** value
+- Workflow continues automatically
+- No error is raised
+
+Timeout is capped server-side at 300s.
+If timeout_seconds on prompt is 0 or exceeds max, 300s is used.
+end note
+
+@enduml