chore(v2): lint pass — black + ruff auto-fix + mypy regressions (#29 v1.1)

Pre-merge lint hygiene on the PR #30 touched files:

- `black` reformatted 9 files (cassette_transport, crud, models, tasks,
  views_api, nip44, all 3 cassette test files, migrations). Cosmetic:
  line lengths, trailing commas, multi-line argument layout.
- `ruff check --fix` cleared 176 of 202 errors auto-fixed. Mostly
  `UP006` `typing.Optional` → `| None` modernization, `I001` import
  sort order, `UP035` typing-extensions cleanup.
- Two new mypy regressions introduced by the migration commit dcb7de0
  fixed:
  - `crud.py:apply_bootstrap_state` — annotated `existing_first: dict
    | None` on the dedup fetch.
  - `tasks.py:_cassette_consumer_tick` — `# type: ignore[arg-type]` on
    the `nostr_client.relay_manager.add_subscription` call; nostrclient's
    upstream typing declares `list[str]` for filters but the actual
    Nostr protocol takes `list[<filter-dict>]`. The runtime accepts it
    (live smoke at 13:43Z dispatched `nip44_decrypt` cleanly through
    this subscription); the typing mismatch is upstream's.

Remaining lint state, intentionally not addressed in this commit
(all pre-existing baseline, not regressions):
- 8 mypy errors in `calculations.py` + the unchanged-by-this-PR parts
  of `crud.py` — pre-existing on v2-bitspire.
- 26 ruff style warnings: 14 are N805 false-positives on Pydantic
  validators (`cls` first-arg is correct for `@validator`-decorated
  methods); 4 are N818 exception-name-suffix preferences on my new
  exception classes (renaming would touch many call sites; keep
  `OperatorIdentityMissing` / `SignerUnavailable` / `RelayUnavailable`
  / `_NostrclientUnavailable` as-is for clarity); 5 are E501 line-too-
  long on docstrings (the long lines are formatted for clarity);
  1 RUF002 unicode-minus in a docstring.

Tests: 155 passed, 1 pre-existing async-plugin failure unchanged.
Live smoke (both publish + consume directions through the bunker)
unaffected — this is purely a code-style pass.

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

tests/test_nip44_v2.py

@@ -32,6 +32,7 @@ from ..nip44 import (
     get_conversation_key,
 )
 
+
 # Helper: derive a compressed-x-coord pubkey hex string from a secret hex.
 def _pub_hex(sec_hex: str) -> str:
     return (
@@ -222,7 +223,10 @@ class TestPaddingFormula:
             (32, 32),
             (33, 64),  # > 32 → next chunk
             (64, 64),
-            (65, 96),  # chunk = 32 for L=65 (next_power(64) = 64; 64//8 = 8; max(32, 8) = 32)
+            (
+                65,
+                96,
+            ),  # chunk = 32 for L=65 (next_power(64) = 64; 64//8 = 8; max(32, 8) = 32)
             (100, 128),
             (128, 128),
             # L=129: next_power(128) = 1<<8 = 256; chunk = max(32, 256//8) = 32;
@@ -230,7 +234,10 @@ class TestPaddingFormula:
             (129, 160),
             (256, 256),  # chunk = 32 for L=256 (next_power(255)=256; max(32, 32) = 32)
             (257, 320),
-            (1000, 1024),  # chunk = 128 for L=1000 (next_power(999)=1024; max(32, 128) = 128)
+            (
+                1000,
+                1024,
+            ),  # chunk = 128 for L=1000 (next_power(999)=1024; max(32, 128) = 128)
         ],
     )
     def test_calc_padded_len(self, plaintext_len, expected_padded):
@@ -300,12 +307,8 @@ _BITSPIRE_FIXTURE = {
             ],
         ],
         "created_at": 1780173222,
-        "pubkey": (
-            "217bdc9a65b571c4d9b59da6227a7aa6ca5bbfd5280af791417c57a79d92852b"
-        ),
-        "id": (
-            "72c09f333386dd4ad6125f8c69823824eea50d8091b694458bcd60701517eece"
-        ),
+        "pubkey": ("217bdc9a65b571c4d9b59da6227a7aa6ca5bbfd5280af791417c57a79d92852b"),
+        "id": ("72c09f333386dd4ad6125f8c69823824eea50d8091b694458bcd60701517eece"),
         "sig": (
             "07ecafacf0169f074e564a999ee1c31446930b43391d007c4a1f9ef7ad890d6c"
             "2aa6e3ecc5318edeb5748fbd64c7ca33407099a97154e2ff7e0c626e48d71925"