fix: Tab Height Guard false-positive on author intent with 'tab' substring

Production bug 2026-05-02 22:19:
Intent 'post author username text (exclude bottom tabs)' contained the
word 'tab' in its parenthetical qualifier. The old check:
    is_tab_intent = 'tab' in intent_lower
matched this intent as a TAB navigation intent, activating the Tab
Height Guard which excluded ALL nodes with center_y < 85% of screen.

This nuked the actual clips_author_username node at y=2012, leaving
only 4 irrelevant items for the VLM → bot stuck in a loop unable to
find the author username.

Fix: Replace substring match with precise regex patterns that only
match real tab navigation intents:
  - 'tap profile tab', 'tap home tab' (tap + word + tab)
  - 'profile tab', 'explore tab' (word + tab)
  - 'tab ...' at start of intent

TDD: Red test added first, reproducing exact production state.
81 perception tests + 172 total tests pass.

GramAddict/core/perception/intent_resolver.py

@@ -61,10 +61,22 @@ class IntentResolver:
         """
         intent_lower = intent_description.lower()
 
-        # Only apply for tab-related intents OR generic interaction intents
-        # We want to aggressively protect against clicking 'Create' / 'Camera' / 'Back' by accident
+        # Only apply for REAL tab navigation intents.
+        # REGRESSION FIX 2026-05-02: "tab" as a substring was too broad.
+        # Intent "post author username text (exclude bottom tabs)" matched
+        # because it contained "tab" → Tab Height Guard nuked the author node.
+        # Now we require specific tab navigation patterns:
+        #   - "tap profile tab", "tap home tab", "explore tab"
+        #   - NOT "exclude bottom tabs", "tabbar", random mentions
+        import re
+        _TAB_PATTERN = re.compile(
+            r"\btap\s+\w+\s+tab\b"       # "tap profile tab", "tap home tab"
+            r"|\b\w+\s+tab\b"            # "profile tab", "explore tab"
+            r"|^tab\b",                   # "tab" at start of intent
+            re.IGNORECASE,
+        )
         filtered = []
-        is_tab_intent = "tab" in intent_lower and "back" not in intent_lower
+        is_tab_intent = bool(_TAB_PATTERN.search(intent_lower)) and "back" not in intent_lower
         is_create_intent = "create" in intent_lower or "camera" in intent_lower or "story" in intent_lower
         # REGRESSION FIX 2026-05-01: Author/username intents must never pick nav tabs
         is_author_intent = any(kw in intent_lower for kw in ["author", "username", "post media"])